What's New in CliSAP/CEN?

Do you know what research your colleagues next door are carrying out? Every two months, “What's new?” lists the latest publications at CliSAP/CEN.

Have you also published recently? Please send us three or four lines that briefly describe your work and the major outcome. Further, we would like to know:

  • Where can your publication be found?
  • How can one get in contact with you

Thanks for sending all to:
foko.cendummy@uni-hamburgdummy2.de (Research Coordination)

 

Date issued: December 2018

Spatio-temporal variability of Antarctic sea-ice thickness and volume obtained from ICESat data using an innovative algorithm

Abstract: We use total (sea ice plus snow) freeboard as estimated from Ice, Cloud and land Elevation Satellite (ICESat) Geophysical Laser Altimeter System (GLAS) observations to compute Antarctic sea-ice thickness and volume. In order to overcome assumptions made about the relationship between snow depth and total freeboard or biases in snow depth products from satellite microwave radiometry, we implement a new algorithm. We treat the sea ice-snow system as one layer with reduced density, which we approximate by means of a priori information about the snow depth to sea-ice thickness ratio. We derive this a priori information directly from ICESat total freeboard data using empirical equations relating in-situ measurements of total freeboard to snow depth or sea-ice thickness. We apply our new algorithm (one-layer method or OLM), which uses the buoyancy equation approach without the need for auxiliary snow depth data, to compute sea-ice thickness for every ICESat GLAS footprint from a valid total freeboard. An improved method for sea-ice volume retrieval is also used to derive ice volume at 6.25 km scale. Spatio-temporal variations of sea-ice thickness and volume are then analyzed in the circumpolar Antarctic as well as its six sea sectors: Pacific Ocean, Indian Ocean, Weddell East, Weddell West, Bell-Amund Sea, and Ross Sea, under both interannual and seasonal scales. Because the OLM algorithm relies on only one parameter, the total freeboard, and is independent of auxiliary snow depth information, it is believed to become a viable alternative sea-ice thickness retrieval method for satellite altimetry.

Keywords: Buoyance equation; Empirical equation; One-layer method; Regional variation; Grid scale

Read: Li, H., Xie, H., Kern, S., Wan, W., Ozsoy, B., Ackley, S., & Hong, Y. (2018). Spatio-temporal variability of Antarctic sea-ice thickness and volume obtained from ICESat data using an innovative algorithm. Remote Sensing of Environment, 219, 44-61. doi:10.1016/j.rse.2018.09.031.

Online: https://doi.org/10.1016/j.rse.2018.09.031

Contact: Stefan Kern (stefan.kerndummy@uni-hamburgdummy2.de)

 

Date issued: December 2018

The role of internal waves in the late Quaternary evolution of the Israeli continental slope

Abstract: Internal waves are widely present in world's oceans propagating in stratified ocean layers such as the seasonal pycnocline. At continental shelves and slopes, breaking of internal waves may create turbulence of sufficient energy to erode and transport sediments. In this study, we investigate the late Pleistocene to Recent impact of internal waves on the morphology of the Israeli Mediterranean continental slope. Based on mooring data, we show that the internal wave spectrum on the upper slope contains significant energy at near-inertial and semidiurnal tidal frequencies. Sediment subbottom profiler data show two fields of nearly contour parallel sediment waves located in water depths of 80 m–130 m and 190 m–350 m, respectively. A zone of flat seafloor morphology and remarkably constant slope inclination of 1.0°–1.2° separates both sediment wave fields. The entire stretch of seafloor between 80 m and 350 m corresponds to depths of major ocean density stratification, supporting the propagation of internal waves. In addition, this area is critically inclined with respect to semidiurnal internal tides and supercritically inclined with respect to near-inertial waves, two scenarios previously related to internal wave breaking. We propose that breaking internal waves control the inclination of the Israeli continental slope and contribute to sediment starvation within the zone of flat seafloor morphology. The formation of sediment waves is attributed to high-frequency trailing internal waves of similar wavelengths as sediment waves, observed within a seismic image of the water column. We correlate subbottom profiler data to a radiocarbon dated sediment core. No sediment waves formed from 16 cal ka–8 cal ka, indicating that the seafloor impact of internal waves ceased during a time of rapid sea level rise and fresh water input in the Eastern Mediterranean realm. The end of this period coincides with the formation of sapropel S1.

Keywords: Internal waves and tides; Reflection seismics; Sapropel S1; Seismic oceanography; Levant Basin; Contour currents

Read: Reiche, S., Hübscher, C., Brenner, S., Betzler, C., & Hall, J. K. (2018). The role of internal waves in the late Quaternary evolution of the Israeli continental slope. Marine Geology, 406, 177-192. doi:10.1016/j.margeo.2018.09.013.

Online: https://doi.org/10.1016/j.margeo.2018.09.013

Contact: Christian Hübscher (christian.huebscherdummy@uni-hamburgdummy2.de)

 

Date issued: December 2018

On the role of horizontal resolution over the Tibetan Plateau in the REMO regional climate model

Abstract: A number of studies have shown that added value is obtained by increasing the horizontal resolution of a regional climate model to capture additional fine-scale weather processes. However, the mechanisms leading to this added value are different over areas with complicated orographic features, such as the Tibetan Plateau (TP). To determine the role that horizontal resolution plays over the TP, a detailed comparison was made between the results from the REMO regional climate model at resolutions of 25 and 50 km for the period 1980–2007. The model was driven at the lateral boundaries by the European Centre for Medium-Range Weather Forecasts Interim Reanalysis data. The experiments differ only in representation of topography, all other land parameters (e.g., vegetation characteristics, soil texture) are the same. The results show that the high-resolution topography affects the regional air circulation near the ground surface around the edge of the TP, which leads to a redistribution of the transport of atmospheric water vapor, especially over the Brahmaputra and Irrawaddy valleys—the main water vapor paths for the southern TP—increasing the amount of atmospheric water vapor transported onto the TP by about 5%. This, in turn, significantly decreases the temperature at 2 m by > 1.5 °C in winter in the high-resolution simulation of the southern TP. The impact of topography on the 2 m temperature over the TP is therefore by influencing the transport of atmospheric water vapor in the main water vapor paths.

Keywords: REMO regional climate model; Validation; High-resolution; Added value; Tibetan Plateau

Read: Xu, J., Koldunov, N., Remedio, A., Sein, D., Zhi, X., Jiang, X., Xu, M., Zhu, X., Fraedrich, K. F., & Jacob, D. (2018). On the role of horizontal resolution over the Tibetan Plateau in the REMO regional climate model. Climate Dynamics, 51, 4525-4542. doi:10.1007/s00382-018-4085-7.

Online: https://doi.org/10.1007/s00382-018-4085-7

Contact: Daniela Jacob (daniela.jacobdummy@hzgdummy2.de)

 

Date issued: December 2018

Weather Extremes, Disasters, and Collective Violence: Conditions, Mechanisms, and Disaster-Related Policies in Recent Research

Abstract: Purpose of Review: Summary of research on the consequences of extreme weather events, which manifest themselves as disasters, for collective violence as well as on policy measures to mitigate such negative effects. Recent Findings: A growing, but contested, majority of studies indicate a slight increase in the likelihood of the occurrence, escalation, and prolongation of collective violence in the wake of disasters. The identification of conditions and mechanisms, some of which increase the likelihood of violence and some of which have the opposite effect, helps us to understand the diversity of outcomes. This includes the consequences of political and humanitarian interventions prior to, during and after disasters, which can overlay local processes. Summary: Conditions and mechanisms shaping the link between disasters and collective violence provide opportunities for policy interventions that are already, or can be, taken to mitigate the consequences of extreme events, increasing or reducing the likelihood and level of collective violence.

Keywords: Climate change; Extreme weather events; Disasters; Collective violence; Armed conflict; Humanitarian assistance; Development assistance; Migration

Read: Brzoska, M. (2018). Weather Extremes, Disasters, and Collective Violence: Conditions, Mechanisms, and Disaster-Related Policies in Recent Research. Current Climate Change Reports, 4(4), 320-329. doi: 10.1007/s40641-018-0117-y

Online: https://doi.org/10.1007/s40641-018-0117-y

Contact: Michael Brzoska (brzoskadummy@ifshdummy2.de)

 

Date issued: November 2018

Mesoscle modelling for meteorological and air pollution applications

Abstract: ‘Mesoscale Modelling for Meteorological and Air Pollution Applications’ combines the fundamental and practical aspects of mesoscale air pollution and meteorological modelling. Providing an overview of the fundamental concepts of air pollution and meteorological modelling, including parameterization of key atmospheric processes, the book also considers equally important aspects such as model integration, evaluation concepts, performance evaluation, policy relevance and user training. Based on research topics that are the most relevant to the development, with models for high resolution meteorology and air quality simulations, and also based on the experience of a large number of meteorological services and air pollution modelling research and user groups, mainly from Europe and North America, ‘Mesoscale Modelling for Meteorological and Air Pollution Applications’ encapsulates the basic concepts of numerical modelling of air quality, model structures, operational characteristics and applications of air pollution mesoscale models for research as well as operational tasks.

Read: Sokhi, R. S., Baklanov, A., & Schlünzen, H. (Eds.). (2018). Mesoscle modelling for meteorological and air pollution applications. London; New York: Anthem Press.

Online: https://www.jstor.org/stable/j.ctv80cdh5

Contact: Heinke Schlünzen (heinke.schluenzendummy@uni-hamburgdummy2.de)

 

Date issued: November 2018

Evolution of Contourite Systems in the Late Cretaceous Chalk Sea Along the Tornquist Zone

Abstract: Based on seismic reflection data the authors reconstructed the paleoceanography of the Late Cretaceous epeiric Chalk Sea in the present day southern Baltic Sea between the Danish and Polish coasts. A south-east directed contour current emerged in the Coniacian or Santonian along the south-western basin margin, creating contourite channels and drifts. A second, deeper and north-west directed counter-flow emerged along and parallel to the Tornquist Zone in the later Campanian, but was strongest in the Maastrichtian. This bottom current moderated the evolution of a drift-moat system adjacent to the elevated Tornquist Zone.

Keywords: Alnarp Valley; Chalk Sea; contourite systems; late Cretaceous; seismo‐stratigraphy; southern Baltic; Tornquist Zone

Read: Hübscher, C., Al Hseinat, M. a., Schneider, M., & Betzler, C. Evolution of contourite systems in the Late Cretaceous Chalk Sea along the Tornquist Zone. Sedimentology,.doi:10.1111/sed.12564

Online: https://doi.org/10.1111/sed.12564

Contact: Christian Hübscher (christian.huebscherdummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

Mechanism of sea-ice expansion in the Indian Ocean sector of Antarctica: Insights from satellite observation and model reanalysis

Abstract: In the backdrop of global warming, Antarctic sea-ice variability showed an overall expansion with the regional heterogeneity of increasing and decreasing patterns. Analysis of satellite derived sea-ice extent, during 1979 to 2015, in the Indian Ocean sector of Antarctica (IOA) revealed expansion of 2.4±1.2% decade-1. We find strengthening of westerly wind during the austral summer (between 50°S to 62°S) facilitated northward advection of a cool and fresh layer. Also, the strong westerly wind cools the upper ocean due to net heat loss from the ocean surface. The combined effect of northward advection of cold fresh layer and net heat loss from the surface, favours sea-ice expansion in the subsequent seasons, in the IOA region, north of 62°S. However, sea-ice retreat was observed near the Kerguelen Plateau, due to upper ocean warming, and hence a non-annular pattern of sea-ice extent in the IOA was observed.

Read: Jena, B., Kumar, A., Ravichandran, M., & Kern, S. (2018). Mechanism of sea-ice expansion in the Indian Ocean sector of Antarctica: Insights from satellite observation and model reanalysis. PLoS One, 13(10): e0203222, pp. 1-16. doi:10.1371/journal.pone.0203222.

Online: https://doi.org/10.1371/journal.pone.0203222

Contact: Stefan Kern (stefan.kerndummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

Evaluation of thermal indices for their applicability in obstacle-resolving meteorology models

Abstract: A thermally comfortable design of outdoor spaces favors social interaction and outdoor activities and thus contributes to the overall well-being of urban dwellers. To assess such a design, obstacle-resolving models (ORM) combined with thermal indices may be used. This paper reviews existing thermal indices to identify those suitable for thermal comfort assessment with ORMs. For the identification, 11 criteria and six index features are derived from literature analysis focusing on the characteristics of human environmental heat exchange, of outdoor urban environments, and of ORMs. An air temperature weighted world population distribution is calculated to derive the minimal air temperature range; a thermal index should cover to be applicable to 95% of the world population. The criteria are applied to 165 thermal indices by reviewing their original publications. Results show that only four thermal indices are suitable to be applied globally in their current form to various outdoor urban environments and also fulfill the requirements of ORMs. The evaluation of the index features shows that they differ with respect to the comprehensiveness of the thermophysiological model, the assessed human response, the treatment of clothing and activity, and the computational costs. Furthermore, they differ in their total application frequency in past ORM studies and in their application frequency for different climatic zones, as a systematic literature analysis of thermal comfort studies employing ORMs showed. By depicting the differences of the thermal indices, this paper provides guidance to select an appropriate thermal index for thermal comfort studies with ORMs.

Keywords: Thermal environment; Outdoor Numerical atmospheric modeling; Index evaluation; Microscale model

Read: Fischereit, J., & Schluenzen, K. H. (2018). Evaluation of thermal indices for their applicability in obstacle-resolving meteorology models. International Journal of Biometeorology, 62, 1887-1900. doi:10.1007/s00484-018-1591-6.

Online: https://doi.org/10.1007/s00484-018-1591-6

Contact: Jana Fischereit (jana.fischereitdummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

Full-field initialized decadal predictions with the MPI Earth System Model: An initial shock in the North Atlantic

Abstract: Our decadal climate prediction system, which is based on the Max-Planck-Institute Earth System Model, is initialized from a coupled assimilation run that utilizes nudging to selected state parameters from reanalyses. We apply full-field nudging in the atmosphere and either full-field or anomaly nudging in the ocean. Full fields from two different ocean reanalyses are considered. This comparison of initialization strategies focuses on the North Atlantic Subpolar Gyre (SPG) region, where the transition from anomaly to full-field nudging reveals large differences in prediction skill for sea surface temperature and ocean heat content (OHC). We show that nudging of temperature and salinity in the ocean modifies OHC and also induces changes in mass and heat transports associated with the ocean flow. In the SPG region, the assimilated OHC signal resembles well OHC from observations, regardless of using full fields or anomalies. The resulting ocean transport, on the other hand, reveals considerable differences between full-field and anomaly nudging. In all assimilation runs, ocean heat transport together with net heat exchange at the surface does not correspond to OHC tendencies, the SPG heat budget is not closed. Discrepancies in the budget in the cases of full-field nudging exceed those in the case of anomaly nudging by a factor of 2–3. The nudging-induced changes in ocean transport continue to be present in the free running hindcasts for up to 5 years, a clear expression of memory in our coupled system. In hindcast mode, on annual to inter-annual scales, ocean heat transport is the dominant driver of SPG OHC. Thus, we ascribe a significant reduction in OHC prediction skill when using full-field instead of anomaly initialization to an initialization shock resulting from the poor initialization of the ocean flow.

Read: Kröger, J., Pohlmann, H., Sienz, F., Marotzke, J., Baehr, J., Köhl, A., Modali, K., Polkova, I., Stammer, D., Vamborg, F., & Müller, W. A. (2018). Full-field initialized decadal predictions with the MPI Earth System Model: An initial shock in the North Atlantic. Climate Dynamics, 51, 2593-2608. doi:10.1007/s00382-017-4030-1.

Online: https://doi.org/10.1007/s00382-017-4030-1

Contact: Jochem Marotzke (jochem.marotzkedummy@mpimet.mpgdummy2.de)

 

Date issued: October 2018

Farmer Perceptions of Climate Change, Observed Trends and Adaptation of Agriculture in Pakistan

Abstract: Farmers’ willingness and ability to adapt agricultural systems depend on their knowledge about changes in climate and perceived risks of extreme events. Using cross-sectional data of 450 farmers collected from three agro-ecological zones of Punjab, Pakistan, this study investigates farmer perceptions of climate change and their agreement with observed climatic trends. In addition, this study explores the correlation between different adaptation stages (perceptions, intentions, and adaptation) and their key drivers using a Multivariate Probit Model. This study also explores the adaptation measures adopted by farmers. The results of the study show that the perceptions of increasing mean temperature match well with locally recorded data. However, a discrepancy is found in some cases between farmer perceptions of rainfall changes and local climate records. Moreover, education, experience, land tenure, land holdings, extension, cooperation, access to weather forecasting, and marketing information are the factors influencing the three adaptation stages. A strong association is found among the three adaptation stages. Particularly, the study confirms the hypothesis that accurate perceptions lead to stronger adaptation intentions compared to underestimated or no perceptions. Further, farmers prefer basic adaptation measures including changing crop varieties, input use and planting dates over advanced measures, such as planting shade trees, soil conservation, and crop diversification. The study recommends providing farmers, especially small landholders and tenants, easy access to information, institutional services and training on the use of advanced measures to reduce negative impacts of climate change at the farm level.

Keywords: Climate change; Accuracy of perceptions; Adaptation intentions; Farm level adaptation Pakistan

Read: Abid, M., Scheffran, J., Schneider, U., & Elahi, E. (in press). Farmer Perceptions of Climate Change, Observed Trends and Adaptation of Agriculture in Pakistan. Environmental Management, available online. doi:10.1007/s00267-018-1113-7.

Online: https://doi.org/10.1007/s00267-018-1113-7

Contact: Jügren Scheffran (juergen.scheffrandummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

Tropical rainfall predictions from multiple seasonal forecast systems

Abstract: We quantify seasonal prediction skill of tropical winter rainfall in 14 climate forecast systems. High levels of seasonal prediction skill exist for year‐to‐year rainfall variability in all tropical ocean basins. The tropical East Pacific is the most skilful region, with very high correlation scores, and the tropical West Pacific is also highly skilful. Predictions of tropical Atlantic and Indian Ocean rainfall show lower but statistically significant scores. We compare prediction skill (measured against observed variability) with model predictability (using single forecasts as surrogate observations). Model predictability matches prediction skill in some regions but it is generally greater, especially over the Indian Ocean. We also find significant inter‐basin connections in both observed and predicted rainfall. Teleconnections between basins due to El Niño–Southern Oscillation (ENSO) appear to be reproduced in multi‐model predictions and are responsible for much of the prediction skill. They also explain the relative magnitude of inter‐annual variability, the relative magnitude of predictable rainfall signals and the ranking of prediction skill across different basins. These seasonal tropical rainfall predictions exhibit a severe wet bias, often in excess of 20% of mean rainfall. However, we find little direct relationship between bias and prediction skill. Our results suggest that future prediction systems would be best improved through better model representation of inter‐basin rainfall connections as these are strongly related to prediction skill, particularly in the Indian and West Pacific regions. Finally, we show that predictions of tropical rainfall alone can generate highly skilful forecasts of the main modes of extratropical circulation via linear relationships that might provide a useful tool to interpret real‐time forecasts.

Read: Scaife, A., Ferranti, L., Alves, O., Athanasiadis, P., Baehr, J., Dequé, M., Dippe, T., Dunstone, N., Fereday, D., Gudgel, R., Greatbatch, R., Hermanson, L., Imada, Y., Jain, S., Kumar, A., MacLachlan, C., Merryfield, W., Müller, W. A., Ren, H.-L., Smith, D., Takaya, Y., Vecchi, G., & Yang, X. (2018). Tropical rainfall predictions from multiple seasonal forecast systems. International Journal of Climatology, early view, available online. doi:10.1002/joc.5855.

Online: https://doi.org/10.1002/joc.5855

Contact: Johanna Baehr (johanna.baehrdummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

Seasonal variations of biogeochemical matter export along the Langtang-Narayani river system in central Himalaya

Abstract: Weathering and suspended matter fluxes of the Langtang Narayani river system in central Nepal Himalaya have been investigated at 16 stations for one year, based on monthly water sampling in the lower reaches and bi-monthly in higher elevation areas, to determine temporal variations of weathering fluxes along an elevation profile between 169 and 3989 m asl. Results indicate that the lower reaches are the dominant places of weathering in the system. The sum of major base cation fluxes is 2.9 to 9.2 higher during the monsoon season compared to the pre-monsoon season. Alkalinity and sea-salt corrected sulfate were the dominant anions (97%). The lowest downstream location exports 1611 tons km−2 yr−1 suspended sediment, 78.56 tons km−2 yr−1 of major cations (Na + K + Mg + Ca), 12.72 tons km−2 yr−1 of silica (4-fold higher than at the middle reaches of the basin), and 1.9 × 106 mol km−2 yr−1 of dissolved inorganic carbon (8.9-fold higher than at the middle reaches). Nitrogen and phosphorus concentrations are low in general and dissolved organic carbon export is within expected ranges. River water pCO2 values are low in general, with exception of those main stem reaches where tributaries with relevant pyrite oxidation processes, and lower pH, alter the pattern locally. Element ratios suggest seasonal shifts in the weathering flux generation, modulated by the monsoon system. During the peak of the monsoon season the most relevant weathering products alkalinity, SO4, Ca and Mg were not diluted, and increased concentrations observed at the lower reaches suggests an enhanced mobilization during this period of the year. Carbonate weathering exceeds silicate weathering along the drainage network and the carbonate- to silicate-cation mol ratio is 3.5 at the outlet. Sulfide oxidation probably enhances weathering rates besides the control of the soil-rock partial pressure of CO2. The ratio of the total alkalinity flux to sea-salt corrected sulfate equivalent flux at the base of the Himalaya at Narayanghat was 5.7. Sea-salt corrected sulfate equivalent export is about the same as the silicate cation-equivalent flux that leaves the system (98%). Therefore, further research on sulfur isotopes might be helpful to support the hypothesis that pyrite oxidation compensates for the idealized CO2-consumption by silicate weathering in the studied area.

Keywords: Weathering; Seasonality; Central Himalaya; Sulfide minerals; Elevation; Langtang – Narayani River

Read: Bhatt, M. P., Hartmann, J., & Acevedo, M. F. (2018). Seasonal variations of biogeochemical matter export along the Langtang-Narayani river system in central Himalaya. Geochimica et Cosmochimica Acta, 238, 208-234. doi: 10.1016/j.gca.2018.06.033

Online: https://doi.org/10.1016/j.gca.2018.06.033

Contact: Jens Hartmann (jens.hartmanndummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

WUDAPT: An Urban Weather, Climate, and Environmental Modeling Infrastructure for the Anthropocene

Abstract: The World Urban Database and Access Portal Tools (WUDAPT) is an international community-based initiative to acquire and disseminate climate relevant data on the physical geographies of cities for modeling and analysis purposes. The current lacuna of globally consistent information on cities is a major impediment to urban climate science toward informing and developing climate mitigation and adaptation strategies at urban scales. WUDAPT consists of a database and a portal system; its database is structured into a hierarchy representing different levels of detail, and the data are acquired using innovative protocols that utilize crowdsourcing approaches, Geowiki tools, freely accessible data, and building typology archetypes. The base level of information (L0) consists of local climate zone (LCZ) maps of cities; each LCZ category is associated with a range of values for model-relevant surface descriptors (roughness, impervious surface cover, roof area, building heights, etc.). Levels 1 (L1) and 2 (L2) will provide specific intra-urban values for other relevant descriptors at greater precision, such as data morphological forms, material composition data, and energy usage. This article describes the status of the WUDAPT project and demonstrates its potential value using observations and models. As a community-based project, other researchers are encouraged to participate to help create a global urban database of value to urban climate scientists.

Read: Ching, J., Mills, G., Bechtel, B., See, L., Feddema, J., Wang, X., . . . Theeuwes, N. (2018). WUDAPT: An Urban Weather, Climate, and Environmental Modeling Infrastructure for the Anthropocene. Bulletin of the American Meteorological Society, 99(9), 1907-1924. doi: 10.1175/bams-d-16-0236.1

Online: https://doi.org/10.1175/BAMS-D-16-0236.1

Contact: Benjamin Bechtel (Benjamin.bechteldummy@uni-hamburgdummy2.de)

 

Date issued: October 2018

Sources of laminated sediments in the northeastern Arabian Sea off Pakistan and implications for sediment transport mechanisms during the late Holocene

Abstract: Laminated sediments of the continental slope off the Makran coast in the northern Arabian Sea are well-known climate archives and record productivity, as well as supply of material from land. Here, we studied sediment core 275KL off Pakistan in concert with sediment trap, dust and river samples in order to characterize and quantify land-derived material deposited in varves and event layers. We analysed grain sizes, mineral assemblages, bulk components and stable isotopes (δ13C, δ18O) of carbonates. In winter, enhanced river discharge is the main source of lithogenic matter contributing the major amounts to the total annual sedimentation of the northern Arabian Sea. During the late summer season, lithogenic matter accumulation is slightly enhanced, probably carried along with the south-eastward blowing Levar winds from the Balochistan and the Sistan Basins and the summer monsoon discharge maximum of perennial streams. C/N ratios and stable carbon and oxygen isotopes could not be used to distinguish between organic matter produced on land and in the ocean, whereas stable carbon and oxygen isotope ratios of carbonates suggest that sedimentation of event layers is dominated by direct inputs from land. Catastrophic denudation and storm events occur on average once every 50 years and lead to sedimentation rates that exceed the mean annual sedimentations of 983 g m−2 yr−1 by 6 to 10 times. Nevertheless, due to their rare occurrence, they contributed only 7% to the total sedimentation during the last ca. 5000 years. End-member modelling of grain sizes in accordance with lithogenic matter accumulation rates and event layer frequencies showed that arid conditions prevailed between 4000 and 5000 a BP while more humid conditions commenced around 2000 ka BP in accordance with the Pacific ENSO record.

Keywords Arabian Sea; ENSO, erosion; grain size; Holocene climate; laminated sediments; lithogenic matter; western disturbances

Read: Forke, S., Rixen, T., Burdanowitz, N., Lückge, A., Ramaswamy, V., Munz, P., . . . Gaye, B. (2019). Sources of laminated sediments in the northeastern Arabian Sea off Pakistan and implications for sediment transport mechanisms during the late Holocene. The Holocene, 29(1), 130-144. doi: 10.1177/0959683618804627

Online: https://doi.org/10.1177/0959683618804627

Contact: Birigt Gaye (birgit.gayedummy@uni-hamburgdummy2.de)

 

Date issued: September 2018

Time dependency of the prediction skill for the North Atlantic subpolar gyre in initialized decadal hindcasts

Abstract: We analyze the time dependency of decadal hindcast skill in the North Atlantic subpolar gyre within the time period 1961–2013. We compare anomaly correlation coefficients and temporal interquartile ranges of total upper ocean heat content and sea surface temperature for three differently initialized sets of hindcast simulations with the global coupled model MPI-ESM. All initializations use weakly coupled assimilation with the same full value nudging in the atmospheric component and different assimilation techniques for oceanic temperature and salinity: (1) ensemble Kalman filter assimilating EN4 observations and HadISST data, (2) nudging of anomalies to ORAS4 reanalysis, (3) nudging of full values to ORAS4 reanalysis. We find that hindcast skill depends strongly on the evaluation time period, with higher hindcast skill during strong multiyear trends, especially during the warming in the 1990s and lower hindcast skill in the absence of such trends. Differences between the prediction systems are more pronounced when investigating any 20-year subperiod within the entire hindcast period. In the ensemble Kalman filter initialized hindcasts, we find significant correlation skill for up to 5–8 lead years, albeit along with an overestimation of the temporal interquartile range. In the hindcasts initialized by anomaly nudging, significant correlation skill for lead years greater than two is only found in the 1980s and 1990s. In the hindcasts initialized by full value nudging, correlation skill is consistently lower than in the hindcasts initialized by anomaly nudging in the first lead years with re-emerging skill thereafter. The Atlantic meridional overturning circulation reacts on the density changes introduced by oceanic nudging, this limits the predictability in the subpolar gyre in the first lead years. Overall, we find that a model-consistent assimilation technique can improve hindcast skill. Further, the evaluation of 20 year subperiods within the full hindcast period provides essential insights to judge the success of both the assimilation and the subsequent hindcast quality.

Read: Brune, S., Düsterhus, A., Pohlmann, H., Müller, W. A., & Baehr, J. (2018). Time dependency of the prediction skill for the North Atlantic subpolar gyre in initialized decadal hindcasts. Climate Dynamics, 51, 1947-1970. doi:10.1007/s00382-017-3991-4.

Online: https://doi.org/10.1007/s00382-017-3991-4

Contact: Sebastian Brune (sebastian.brunedummy@uni-hamburgdummy2.de)

 

Date issued: September 2018

Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals

Abstract: Current mitigation efforts and existing future commitments are inadequate to accomplish the Paris Agreement temperature goals. In light of this, research and debate are intensifying on the possibilities of additionally employing proposed climate geoengineering technologies, either through atmospheric carbon dioxide removal or farther-reaching interventions altering the Earth’s radiative energy budget. Although research indicates that several techniques may eventually have the physical potential to contribute to limiting climate change, all are in early stages of development, involve substantial uncertainties and risks, and raise ethical and governance dilemmas. Based on present knowledge, climate geoengineering techniques cannot be relied on to significantly contribute to meeting the Paris Agreement temperature goals.

Read: Lawrence, M. G., Schäfer, S., Muri, H., Scott, V., Oschlies, A., Vaughan, N. E., Boucher, O., Schmidt, H., Haywood, J., & Scheffran, J. (2018). Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals. Nature Communications, 9: 3734. doi:10.1038/s41467-018-05938-3.

Online: https://doi.org/10.1038/s41467-018-05938-3

Contact: Jürgen Scheffran (juergen.scheffrandummy@uni-hamburgdummy2.de)

 

Date issued: September 2018

Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern Siberia

Abstract: Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide (CO2) and methane (CH4) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production as a result of degrading ice-rich permafrost deposits from three locations in the northeastern Siberian Laptev Sea region. The deposits span a period of about 55kyr from the last glacial period and Holocene interglacial. Samples from all three locations were incubated under aerobic and anaerobic conditions for 134 days at 4°C. Greenhouse gas production was generally higher in deposits from glacial periods, where 0.2%–6.1% of the initially available OC was decomposed to CO2. In contrast, only 0.1%–4.0% of initial OC was decomposed in permafrost deposits from the Holocene and the late glacial transition. Within the deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the greenhouse gas production potentials over longer periods, deposits from two locations were incubated for a total of 785 days. However, more than 50% of total CO2 production over 785 days occurred within the first 134 days under aerobic conditions, while 80% were produced over the same period under anaerobic conditions, which emphasizes the nonlinearity of the OC decomposition processes. Methanogenesis was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than CO2 production.

Read: Walz, J., Knoblauch, C., Tigges, R., Opel, T., Schirrmeister, L., and Pfeiffer, E.-M. (2018) Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern Siberia, Biogeosciences, 15, 5423-5436, doi:10.5194/bg-15-5423-2018.

Online: https://doi.org/10.5194/bg-15-5423-2018

Contact: Josefine Walz (josefine.walzdummy@uni-hamburgdummy2.de)

 

Date issued: August 2018

Regime Shifts – A Global Challenge for the Sustainable Use of Our Marine Resources

Abstract: Over the last decades many marine systems have undergone drastic changes often resulting in new ecologically structured and sometimes economically less valuable states. In particular, the additive effects of anthropogenic stressors (e.g., fishing, climate change) seem to play a fundamental role in causing unexpected and sudden shifts between system states, generally termed regime shifts. Recently, many examples of regime shifts have been documented worldwide and their mechanisms and consequences have been vigorously discussed. Understanding causes and mechanisms of regime shifts is of great importance for the sustainable use of natural resources and their management, especially in marine ecosystems. Hence, we conducted a session entitled “Ecosystem dynamics in a changing world, regime shifts and resilience in marine communities” during the 8th YOUMARES conference (Kiel, 13–15th September 2017) to present regime shifts concepts and examples to a broad range of marine scientists (e.g., biologists and/or ecologists, physicists, climatologists, sociologists) and highlight their importance for the marine ecosystems worldwide. In this chapter, we first provide examples of regime shifts which have occurred over the last decades in our oceans and discuss their potential implications for the sustainable use of marine resources; then we review regime shift theory and associated concepts. Finally, we review recent advances and future challenges to integrate regime shift theory into holistic marine ecosystem-based management approaches.

Read: Sguotti C., Cormon X. (2018) Regime Shifts – A Global Challenge for the Sustainable Use of Our Marine Resources. In: Jungblut S., Liebich V., Bode M. (eds) YOUMARES 8 – Oceans Across Boundaries: Learning from each other. Springer, Cham

Online: https://doi.org/10.1007/978-3-319-93284-2_11

Contact: Camilla Sguotti (camilla.sguottidummy@uni-hamburgdummy2.de)

 

Date issued: August 2018

Temperature and CO2 dependency of global carbonate weathering fluxes – Implications for future carbonate weathering research

Abstract: Carbonate weathering and transfer of carbon towards the coastal zone is one of the relevant sinks for atmospheric CO2, controlled by hydrology, ecosystem respiration, river water degassing, and further factors. Specifically, the connection between the soil-rock system to the river systems and instream processes affecting the weathering product fluxes remain under-researched. Based on constraints for soil-rock PCO2, river PCO2, and an identified dependence of river alkalinity on temperature, this work tested which controls should be considered at the global scale to accomplish a more holistic carbonate rock weathering model. Compiled river data suggests that with increasing land temperature, above approximately 11 °C, the amount of instream alkalinity in carbonate catchments decreases due to the temperature effect on the carbonate system, while the converse holds true at lower temperatures. Latter is in accordance with calcite dissolution controlled by soil-rock PCO2 estimates based on ecosystem respiration. In addition, the type of the weathering system (open, semi-closed to closed system with respect to CO2) was identified to be highly relevant for global weathering estimations. Open systems seem to be the most dominant boundary condition of calcite weathering in the soil profile. Tropical areas with thick soil layers, however, cause the carbonate weathering system to shift from open to semi-closed or closed system conditions. The findings support that calcite weathering fluxes in the soil profile are higher than the fluxes to the ocean transported by rivers. Furthermore, an increase in mean land temperature does not necessarily translate into an increase of lateral weathering fluxes because it might have an influence on soil development, discharge, CO2 degassing, soil respiration and calcite dissolution. All these named factors need to be addressed to be able to quantify global carbonate weathering fluxes and to assess the sensitivity of carbonate weathering fluxes on climate variability. Future works should focus on collecting more temporal river chemistry data, mainly in tropical regions, to understand the main mechanism causing the observed decrease of alkalinity concentration with temperature.

Keywords: Carbonate system; Partial pressure of CO2; Carbon cycle; Global model

Read: Romero-Mujalli, G., Hartmann, J., & Börker, J. (2018). Temperature and CO2 dependency of global carbonate weathering fluxes – Implications for future carbonate weathering research. Chemical Geology. doi:10.1016/j.chemgeo.2018.08.010

Online: https://doi.org/10.1016/j.chemgeo.2018.08.010

Contact: Gibran Romero Mujalli (gibran.romero.mujallidummy@uni-hamburgdummy2.de)

 

Date issued: August 2018

The Concept of Large‐Scale Conditioning of Climate Model Simulations of Atmospheric Coastal Dynamics: Current State and Perspectives

Abstract: We review the state of dynamical downscaling with scale-constrained regional and global models. The methodology, in particular spectral nudging, has become a routine and well-researched tool for hindcasting climatologies of sub-synoptic atmospheric disturbances in coastal regions. At present, the spectrum of applications is expanding to other phenomena, but also to ocean dynamics and to extended forecasting. Additionally, new diagnostic challenges are appearing such as spatial characteristics of small-scale phenomena such as Low Level Jets.

Keywords: dynamical downscaling; spectral nudging; coastal phenomena; storms

Read: Von Storch, H., Cavicchia, L., Feser, F., & Li, D. (2018). The Concept of Large‐Scale Conditioning of Climate Model Simulations of Atmospheric Coastal Dynamics: Current State and Perspectives. Atmosphere, 9(9), 337. doi:10.3390/atmos9090337

Online: https://doi.org/10.3390/atmos9090337

Contact: Frauke Feser (frauke.feser@hzg.de)

 

Date issued: July 2018

Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates

Abstract: Relating the temperature dependence of photosynthetic biomass production to underlying metabolic rates in autotrophs is crucial for predicting the effects of climatic temperature fluctuations on the carbon balance of ecosystems. We present a mathematical model that links thermal performance curves (TPCs) of photosynthesis, respiration, and carbon allocation efficiency to the exponential growth rate of a population of photosynthetic autotroph cells. Using experiments with the green alga, Chlorella vulgaris, we apply the model to show that the temperature dependence of carbon allocation efficiency is key to understanding responses of growth rates to warming at both ecological and longer-term evolutionary timescales. Finally, we assemble a dataset of multiple terrestrial and aquatic autotroph species to show that the effects of temperature-dependent carbon allocation efficiency on potential growth rate TPCs are expected to be consistent across taxa. In particular, both the thermal sensitivity and the optimal temperature of growth rates are expected to change significantly due to temperature dependence of carbon allocation efficiency alone. Our study provides a foundation for understanding how the temperature dependence of carbon allocation determines how population growth rates respond to temperature.

Read: García-Carreras, B., Sal, S., Padfield, D., Kontopoulos, D.-G., Bestion, E., Schaum, C.-E., . . . Pawar, S. (2018). Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates. Proceedings of the National Academy of Sciences, 115(31), E7361-E7368. doi: 10.1073/pnas.1800222115.

Online: https://doi.org/10.1073/pnas.1800222115

Contact Elisa Schaum (elisa.schaumdummy@uni-hamburgdummy2.de)

 

Date issued: July 2018

Modeled larval fish prey fields and growth rates help predict recruitment success of cod and anchovy in the North Sea

Abstract: We introduce a new, coupled modeling approach for simulating ecosystem-wide patterns in larval fish foraging and growth. An application of the method reveals how interplay between temperature and plankton dynamics during 1970-2009 impacted a cold-water species (Atlantic cod Gadus morhua) and a warm-water species (European anchovy Engraulis encrasicolus) in the North Sea. Larval fish growth rates were estimated by coupling models depicting trait-based foraging and bioenergetics of individuals, spatiotemporal changes in their prey field, and the biogeochemistry and hydrodynamics of the region. The biomass composition of modeled prey fields varied from 89% nano-, 10% micro-, and 1% mesoplankton to 15% nano-, 20% micro-, and 65% mesoplankton. The mean slope of the normalized biomass size spectrum was near -1.2, consistent with theoretical and empirical estimates. Median larval fish growth rates peaked in June for cod (24% d-1) and in July for anchovy (17% d-1). Insufficient prey resources played a substantial role in limiting the growth rates of cod larvae. Anchovy were consistently limited by cold temperatures. Faster median larval growth during specific months was significantly (p < 0.05) positively associated with detrended (i.e. higher than expected) juvenile recruitment indices in cod (rank correlation Kendall’s tau = 22%) and anchovy (tau = 42%). For cod, the most predictive month was February, which was also when food limitation was most prevalent. The continued development of modeling tools based on first principles can help further a mechanistic understanding of how changes in the environment affect the productivity of living marine resources.

Keywords: Fish larvae; Plankton; Model; Bottom-up processes; Prey availability; Growth; Recruitment; Cod; Anchovy; North Sea

Read: Huebert KB, Pätsch J, Hufnagl M, Kreus M, Peck MA (2018) Modeled larval fish prey fields and growth rates help predict recruitment success of cod and anchovy in the North Sea. Mar Ecol Prog Ser 600:111-126. doi:10.3354/meps12615.

Online: https://doi.org/10.3354/meps12615

Contact: Johannes Pätsch (johannes.paetschdummy@uni-hamburgdummy2.de)

 

Date issued: July 2018

Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative

Abstract:

Read: Paul, S., Hendricks, S., Ricker, R., Kern, S., & Rinne, E. (2018). Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative. The Cryosphere, 12(7), 2437-2460. doi: 10.5194/tc-12-2437-2018

Online: https://doi.org/10.5194/tc-12-2437-2018

Contact: Stefan Kern (stefan.kerndummy@uni-hamburgdummy2.de)

 

Date issued: June 2018

Poor ecological representation by an expensive reserve system: evaluating 35 years of marine protected area expansion

Abstract: Global areal protection targets have driven a dramatic expansion of the marine protected area (MPA) estate. We analyzed how cost‐effective global MPA expansion has been since the inception of the first global target (set in 1982) in achieving ecoregional representation. By comparing spatial patterns of MPA expansion against optimal MPA estates using the same expansion rates, we show the current MPA estate is both expensive and ineffective. Although the number of ecoregions represented tripled and 12.7% of national waters was protected, 61% of ecoregions and 81% of countries are not 10% protected. Only 10.3% of the national waters of the world would be sufficient to protect 10% of each ecoregion if MPA growth since 1982 strategically targeted underrepresented ecoregions. Unfortunately 16.3% of national waters are required for the same representative target if systematic protection started in 2016 (an extra 3.6% on top of 12.7%). To avoid the high costs of adjusting increasingly biased MPA systems, future efforts should embrace target‐driven systematic conservation planning.

Read: Jantke K., Jones K.R., Allan J.R., Chauvenet A.L.M., Watson J.E.M., Possingham H.P. (2018). Poor ecological representation by an expensive reserve system: evaluating 35 years of marine protected area expansion. Conservation Letters, DOI: 10.1111/conl.12584.

Online: https://doi.org/10.1111/conl.12584

Contact: Kerstin Jantke (kerstin.jantkedummy@uni-hamburgdummy2.de)

Date issued: August 2018

They sow the wind and reap bioenergy – Implications of the German energy transition on coastal communities in Schleswig‐Holstein, Germany

Abstract: The catastrophic earthquake in Japan in March 2011 which triggered the nuclear meltdown of the plant in Fukushima led to a cascade of consequences that included a drastic change in German energy policy, aiming at the complete phase-out of nuclear energy by the mid-2020s (Kominek & Scheffran, 2012). In order to achieve this ambitious goal, there has to be a substantial substitution of energy production using renewable sources such as wind energy, solar energy or bioenergy. Even before the 2011 decision to initiate the energy transition in Germany (“Energiewende”), there had already been a considerable development of renewable energy sources in Germany (Wüstenhagen & Bilharz, 2006). The low-lying flat coastal areas of northern Germany are particularly suited for energy production from wind, but there is considerable intra-state heterogeneity, with wind-energy production being most prominent in the coastal counties along the North Sea coast and in Ostholstein near the Baltic Sea (Goetzke & Rave, 2016). Furthermore, large parts of the coastal areas are also used by agriculture, which makes it relatively easy to engage in biomass production for bioenergy plants. Both kinds of energy sources have become increasingly important in the German energy mix since the beginning of the 21st century. Additionally, the potential for energy production from agricultural leftovers such as straw is substantial in Schleswig-Holstein and could become an important alternative to the growth of energy plants in the northernmost German state (Weiser et al., 2014).

Read: Link, M., Scheffran, J., & Shu, K. (2018). They sow the wind and reap bioenergy – Implications of the German energy transition on coastal communities in Schleswig ‐ Holstein, Germany. In P. C. Heidkamp, & J. Morrissey (Eds.), Towards Coastal Resilience and Sustainability. Bosa Roca: Taylor & Francis.

Online: https://www.taylorfrancis.com/books/e/9780815358664/chapters/10.4324%2F9780429463723-18

Date issued: August 2017

Tracking Fatty Acids From Phytoplankton to Jellyfish Polyps Under Different Stress Regimes: A Three Trophic Levels Experiment

Abstract: The impacts of biochemicals driving food web processes are under investigation for just the last few decades. In addition, as jellyfish are drawing increasing attentions because of their mass developments and of their potential capacity of driving food web structures and energy flow by “top-down” and “bottom-up” controls. We here show that the provision with the biochemical complex thiamin (vitamin B1) to the common phytoplankton Rhodomonas baltica altered its fatty acid (FA) pattern toward ω3-highly-unsaturated FAs (ω3-HUFA) and that this pattern was further transferred up to the zooplankton consumer, the copepod Acartia tonsa. However, polyps of the Jellyfish Aurelia aurita feeding on A. tonsa only had a low relative ω3-HUFA content, especially due to a reduction in 22:6ω3 (DHA), but elevated levels of 20:4ω6 (ARA). The high proportion of the ω-6 HUFA, ARA in polyps may provide evidence for preferential conversion of ARA in polyps, eventually from DHA in a so far unknown pathway. In contrast to A. tonsa, newly hatched A. salina nauplii used as food for A. aurita polyps were almost devoid of HUFA, but contained high levels of C18 polyunsaturated FAs (C18-PUFA). Consequently, polyps feeding on them contained few HUFA, while high levels of C18-PUFA predominated. This suggests that A. aurita polyps cannot efficiently convert ω3 C18-PUFA to ω3-HUFA. In addition, besides a decrease in saturated FAs, especially an increase in HUFA in A. aurita polyps with decreasing temperature was observed, for which the dietary provision with HUFA seemed to be critical. Altering the FA pattern as a response of temperature reflects an adaptation to seasonal changes and may be related to their life history plasticity.

Read: Chi X, Javidpour J, Sommer, U and Mueller-Navarra D (2018) Tracking Fatty Acids From Phytoplankton to Jellyfish Polyps Under Different Stress Regimes: A Three Trophic Levels Experiment. Front. Ecol. Evol. 6:118. doi: 10.3389/fevo.2018.00118.

Online: https://doi.org/10.3389/fevo.2018.00118

Contact: Dörthe Müller-Navarra (doerthe.mueller-navarradummy@uni-hamburgdummy2.de)

Date issued: August 2018

Fluctuation analysis of the atmospheric energy cycle

Abstract: The atmosphere gains available potential energy by solar radiation and dissipates kinetic energy mainly in the atmospheric boundary layer. We analyze the fluctuations of the global mean energy cycle defined by Lorenz in a simulation with a simplified hydrostatic model. The energy current densities are well approximated by the generalized Gumbel distribution and the Generalized Extreme Value (GEV) distribution. In an attempt to assess the fluctuation relation of Evans, Cohen, and Morriss we define entropy production by the injected power and use the GEV location parameter as a reference state. The fluctuation ratio reveals a linear behavior in a finite range.

Read: Blender, R., Gohlke, D., & Lunkeit, F. (2018). Fluctuation analysis of the atmospheric energy cycle. Physical Review E, 98: 023101, pp. 1-7. doi:10.1103/PhysRevE.98.023101.

Online: https://doi.org/10.1103/PhysRevE.98.023101

Date Issued: August 2018

Understanding how China is championing climate change mitigation

Abstract: This comment deals with the question of how current political regimes could effectively contribute to the mitigation of climate change—and why this might happen. Against the backdrop of the US government’s announcement to withdraw from the Paris agreement, the rise of populist governments across the globe, and the slow progress of energy transformation projects in pluralistic countries, this paper focuses on China’s potential role in climate change mitigation. Since 2008, the Chinese government has switched to a proactive stance on climate governance and low-carbon development. Due to significant improvements in CO2 efficiency and a clear slow-down in the rise of its annual total CO2 emissions, China is increasingly perceived as a new low-carbon champion and appears to be in a position to take over global climate mitigation leadership. This comment examines the drivers behind current low-carbon developments in China and tests the assumption that China’s state-led non-participatory authoritarianism will effectively offer a solution to the global climate problem. Any switch to low-carbon development rests on complex societal preconditions and requirements. This paper discusses the reasons why the likelihood that the Chinese authoritarian regime will be effective over the long-term in lowering greenhouse gas emissions is uncertain at best—because of internal contestations, low public and private-business participation, and countervailing strategies to secure China’s global market positions. Understanding the foundations and nature of China’s climate change mitigation championship has important implications for fostering low-carbon developments in all political regimes.

Read: Engels, A (2018). Understanding how China is championing climate change migration. Palgrave Communications, 4, 101, doi:10.57/s41599-018-0150-4.

Online: https://doi.org/10.1057/s41599-018-0150-4

Date issued: August 2018

Robust and non-robust impacts of atmospheric cloud-radiative interactions on the tropical circulation and its response to surface warming

Abstract: The impact of cloud‐radiative interactions on the tropical circulation and its response to surface warming are studied in aquaplanet model simulations with prescribed sea‐surface temperatures from eight global atmosphere models. Simulations with enabled and disabled cloud‐radiative interactions are compared. In a present‐day‐like climate, the presence of cloud‐radiative interactions strengthens the Hadley cell, narrows and strengthens tropical ascent, and widens subtropical descent. These cloud impacts are robust across models and are shown to be related to the energetics and mass constraints of the tropical atmosphere. Cloud‐radiative interactions have no robust impact on the circulation response to surface warming, but amplify model differences in the response of the ascent and the Hadley cell strength. The lack of robust cloud impacts is consistent with the fact that surface warming‐induced changes in atmospheric cloud‐radiative effects are small compared to the cloud‐radiative effects in the present‐day‐like climate.

Keywords: cloud‐radiative interactions; tropical circulation; Hadley cell; COOKIE; climate change; global climate model

Read: Albern, N., Voigt, A., Buehler, S. A., & Grützun, V. (in press). Robust and non‐robust impacts of atmospheric cloud‐radiative interactions on the tropical circulation and its response to surface warming. Geophysical Research Letters, 1-28. doi:10.1029/2018gl079599.

Online: https://doi.org/10.1029/2018GL079599

Date issued: July 2018

Statistical-dynamical downscaling of the urban heat island in Hamburg, Germany

Abstract: Regional climate models provide climate projections on a horizontal resolution in the order of 10 km. This is too coarse to sufficiently simulate urban climate related phenomena such as the urban heat island (UHI). Therefore, regional climate projections need to be downscaled. A statistical-dynamical method for the UHI was developed and applied to provide urban climate results at a high resolution with little computational costs. For the downscaling, weather situations relevant for the UHI are determined. This is done by combining objective weather pattern classification based on a k-means cluster analysis of ERA-40 reanalysis data and a regression-based statistical model of the observed UHI of Hamburg. The resulting days for each weather pattern are simulated with the mesoscale meteorological model METRAS at 1 km horizontal resolution. To obtain the average UHI for a climate period, the mesoscale model results are statistically recombined weighted by the frequency of the corresponding weather patterns. This is done for present-day climate (1971–2000) using reanalysis data to yield the current climate UHI. For the future climate periods 2036–2065 and 2070–2099 the results of regional climate projections are employed. Results are presented for Hamburg (Germany). The present day UHI pattern is well reproduced compared to temperature data based on floristic mapping data. The magnitude of the early night-time UHI is underestimated when compared to observed minimum temperature differences. The future UHI pattern does only slightly change towards the end of the 21st century based on A1B scenario results of the RCMs REMO and CLM. However, for CLM the number of days with high UHI intensities significantly increases mainly due to a decrease in near-surface relative humidity.

Keywords: downscaling; statistical-dynamical downscaling; climate modelling; numerical model; weather pattern; urban heat island

Read: Hoffmann, P., Schoetter, R., & Schlünzen, H. (2018). Statistical-dynamical downscaling of the urban heat island in Hamburg, Germany. Meteorologische Zeitschrift, 27, 89-109. doi:10.1127/metz/2016/0773.

Online: https://doi.org/10.1127/metz/2016/0773

Contact: Heinke Schlünzen (heinke.schluenzendummy@uni-hamburgdummy2.de)

Date issued: July 2018

Opportunity makes opinion leaders: analyzing the role of first-hand information in opinion leadership in social media networks

Abstract: Theorizing information flows is at the heart of traditional communication theories such as the two-step flow of communication and the concept of opinion leadership. Social media have fundamentally altered how information reaches people. This study examines opinion leadership in social media networks and argues that opinion leaders may no longer need to rely on information provided by the media if they have access to first-hand information. To test this assumption empirically, we used data from the 2015 United Nations Climate Change Conference (COP21). Attendees of the conference had direct information about what was happening, which they were able to share live with their followers via social media. We used geo-located tweets to identify Twitter users who attended the COP21 summit. We then located these users in a data set of tweets that were collected based on the main conference hashtag (#COP21) and represent the wider social media debate on the conference. Our results, which are based on network analysis measures and Twitter user data, show that COP21 participants were more central actors compared to the average user in the network, and that they were more likely to have brokering positions. They were also more involved in the debate and received more attention from other users. We used automated content analysis to divide COP21 participants into different actor types and performed the analysis by actor group. The results show only minor differences across the actors and support the robustness of our analysis.

Keywords: Communication studies; social media; opinion leadership; social networking; climate change; Twitter

Read: Brüggemann, M., & Walter, S. (in press). Opportunity makes opinion leaders: analyzing the role of first-hand information in opinion leadership in social media networks. Information, Communication & Society, 1-22. doi:10.1080/1369118X.2018.1500622.

Online: https://doi.org/10.1080/1369118X.2018.1500622

Date issued: July 2018

Atlantic Ocean Heat Transport Influences Interannual-to-Decadal Surface Temperature Predictability in the North Atlantic Region

Abstract: covering the period 1901–2010 shows that Atlantic northward ocean heat transport (OHT) at 50°N influences surface temperature variability in the North Atlantic region for several years. Three to ten years after strong OHT phases at 50°N, a characteristic pattern of sea surface temperature (SST) anomalies emerges: warm anomalies are found in the North Atlantic and cold anomalies emerge in the Gulf Stream region. This pattern originates from persistent upper-ocean heat content anomalies that originate from southward-propagating OHT anomalies in the North Atlantic. Interannual-to-decadal SST predictability of yearly initialized hindcasts is linked to this SST pattern: when ocean heat transport at 50°N is strong at the initialization of a hindcast, SST anomaly correlation coefficients in the northeast Atlantic at lead years 2–9 are significantly higher than when the ocean heat transport at 50°N is weak at initialization. Surface heat fluxes that mask the predictable low-frequency oceanic variability that influences SSTs in the northwest Atlantic after strong OHT phases, and in the northwest and northeast Atlantic after weak OHT phases at 50°N lead to zonally asymmetrically predictable SSTs 7–9 years ahead. This study shows that the interannual-to-decadal predictability of North Atlantic SSTs depends strongly on the strength of subpolar ocean heat transport at the start of a prediction, indicating that physical mechanisms need to be taken into account for actual temperature predictions.

Keywords: Meridional overturning circulation; Surface temperature; Climate prediction; Decadal variability

Read: Borchert, L., Müller, W. A., & Baehr, J. (2018). Atlantic Ocean heat transport influences interannual-to-decadal surface temperature predictability in the North Atlantic region. Journal of Climate, 31, 6763-6782. doi:10.1175/JCLI-D-17-0734.1.

Online: https://doi.org/10.1175/JCLI-D-17-0734.1

Date issued: July 2018

What do people know about climate change — and how confident are they? On measurements and analyses of science related knowledge

Abstract: The measurement and analysis of people's knowledge on scientific topics, such as climate change, is challenging for researchers. One reason is that objectives are multi-dimensional and that probability is inherent. Moreover, uncertainties can exist on the individual's level among the public, but are rarely grasped by existing scales. Therefore, researchers must thoroughly consider what to measure and how. This paper theorizes five different dimensions of climate change knowledge. Three response scales including different degrees of confidence are applied on data from a German online survey (n=935); empirical results of multivariate regression analyses on attitudes are compared. Results highlight the importance of distinctively measuring dimensions and types of knowledge.

Keywords: Environmental communication; Public understanding of science and technology; Science and media

Read: Hoppe, I., Taddicken, M., & Reif, A. (2018). What do people know about climate change — and how confident are they? On measurements and analyses of science related knowledge. Journal of Science Communication (Jcom), 17(3): A01, pp. 1-26. doi:10.22323/2.17030201.

Online: doi.org/10.22323/2.17030201

Date issued: July 2018

Inter-channel uniformity of a microwave sounder in space

Abstract: We analyzed intrusions of the Moon in the deep space view of the Advanced Microwave Sounding Unit-B on the NOAA-16 satellite and found no significant discrepancies in the signals from the different sounding channels between 2001 and 2008. However, earlier investigations had detected biases of up to 10K, by using simultaneous nadir overpasses of NOAA-16 with other satellites. These discrepancies in the observations of Earth scenes cannot be due to non-linearity of the receiver or contamination of the deep space view without affecting the signal from the Moon as well. As neither major anomalies of the on-board calibration target nor the local oscillator were present, we consider radio frequency interference in combination with a strongly decreasing gain the most obvious reason for the degrading photometric stability. By means of the chosen example we demonstrate the usefulness of the Moon for investigations of the performance of microwave sounders in flight.

Read: Burgdorf, M., Hans, I., Prange, M., Lang, T., & Buehler, S. A. (2018). Inter-channel uniformity of a microwave sounder in space. Atmospheric Measurement Techniques, 11, 4005-4014. doi:10.5194/amt-11-4005-2018.

Online: https://doi.org/10.5194/amt-11-4005-2018

Date issued: July 2018

OceanRAIN, a new in-situ shipboard global ocean surface-reference dataset of all water cycle components

Abstract: OceanRAIN—the Ocean Rainfall And Ice-phase precipitation measurement Network—provides in-situ along-track shipboard data of precipitation, evaporation and the resulting freshwater flux at 1-min resolution over the global oceans from June 2010 to April 2017. More than 6.83 million minutes with 75 parameters from 8 ships cover all routinely measured atmospheric and oceanographic state variables along with those required to derive the turbulent heat fluxes. The precipitation parameter is based on measurements of the optical disdrometer ODM470 specifically designed for all-weather shipboard operations. The rain, snow and mixed-phase precipitation occurrence, intensity and accumulation are derived from particle size distributions. Additionally, microphysical parameters and radar-related parameters are provided. Addressing the need for high-quality in-situ precipitation data over the global oceans, OceanRAIN-1.0 is the first comprehensive along-track in-situ water cycle surface reference dataset for satellite product validation and retrieval calibration of the GPM (Global Precipitation Measurement) era, to improve the representation of precipitation and air-sea interactions in re-analyses and models, and to improve understanding of water cycle processes over the global oceans.

Read: Klepp, C., Michel, S., Protat, A., Burdanowitz, J., Albern, N., Kähnert, M., Dahl, A., Louf, V., Bakan, S., & Buehler, S. A. (2018). OceanRAIN, a new in-situ shipboard global ocean surface-reference dataset of all water cycle components. Scientific Data, 5: 180122. doi:10.1038/sdata.2018.122.

Online: https://doi.org/10.1038/sdata.2018.122

Date issued: June 2018

Evaluating a stochastic parametrization for a fastslow system using the Wasserstein distance

Abstract: Constructing accurate, flexible, and efficient parametrizations is one of the great challenges in the numerical modeling of geophysical fluids. We consider here the simple yet paradigmatic case of a Lorenz 84 model forced by a Lorenz 63 model and derive a parametrization using a recently developed statistical mechanical methodology based on the Ruelle response theory. We derive an expression for the deterministic and the stochastic component of the parametrization and we show that the approach allows for dealing seamlessly with the case of the Lorenz 63 being a fast as well as a slow forcing compared to the characteristic timescales of the Lorenz 84 model. We test our results using both standard metrics based on the moments of the variables of interest as well as Wasserstein distance between the projected measure of the original system on the Lorenz 84 model variables and the measure of the parametrized one. By testing our methods on reduced-phase spaces obtained by projection, we find support for the idea that comparisons based on the Wasserstein distance might be of relevance in many applications despite the curse of dimensionality.

Read: Vissio, G. and Lucarini, V. (2018) Evaluating a stochastic parametrization for a fastslow system using the Wasserstein distance. Nonlinear Processes in Geophysics, 25 (2). pp. 413-427. doi:10.5194/npg-25-413-2018.

Online: https://doi.org/10.5194/npg-25-413-2018

Date issued: June 2018

A mathematics inspired notation of scales in the climate system

Abstract: Conducting integrated climate research with involvement of such diverse disciplines as mathematics, meteorology, oceanography, economics, geology, biology, social, and communication sciences poses great challenges to the underlying nomenclature and methodology. In this article, we give a definition of the notion of scales, which is a central term in the geosciences, but not so familiar to social sciences or economics. We start with defining agents, involved in a specific subject of study, determined by their attributes or states. We move on to understand processes and phenomena as maps and subsets of image sets. With this and the introduction of metrics, we can measure sizes of phenomena and processes and finally define scales. Several examples illustrate our definition. An attempt is made to motivate a notion of scale interaction. This concept has proved useful in an interdisciplinary teaching project.

Keywords: climate; scale; scale interaction; resonance; interdisciplinary research

Read: Behrens, J. (2018). A mathematics inspired notation of scales in the climate system. Geosciences, 8: UNSP 213. doi:10.3390/geosciences8060213.

Online: https://doi.org/doi:10.3390/geosciences8060213

Date issued: June 2018

Multi-decadal trend and decadal variability of the regional sea level over the Indian Ocean since the 1960s: Roles of climate modes and external forcing

Abstract: Previous studies suggest that anthropogenic warming has affected the multi-decadal trend patterns of sea level over the Indian Ocean (IO). This effect, however, has not been quantified. Using observational datasets combined with large ensemble experiments from two climate models, this paper assesses the effects of natural internal variability versus external forcing on the observed, multi-decadal trend pattern and the decadal sea level anomaly (SLA) of the IO since the 1960s. Because the global mean sea level rise (SLR), which results largely from external forcing, has been removed before the examination, the paper focuses on the regionally uneven distribution of trend and SLA. The impacts of climate modes are quantified using a Bayesian Dynamic Linear Model. For the regional trend pattern of 1958–2005, the effects of internal variability dominate external forcing. Over the Seychelles area where sea-level variations obtain the maximum, internal variability (external forcing) contributes 81% (19 ± 2.4%) of the observed trend. For decadal SLA, internal variability is the predominant cause, with a standard deviation (STD) ratio of externally forced/observed SLA being 18 ± 17% over Seychelles and 17 ± 11% near the Indonesian Throughflow (ITF) area. Climate modes account for most observed SLA during boreal winter, with the total effects of decadal ENSO, Indian Ocean Dipole (IOD), and monsoon accounting for 78–86% of the observed STD near the Seychelles region, ITF area, and coasts of Sumatra and the Bay of Bengal. During summer, climate modes explain 95% of observed STD near the ITF but only 58–67% in other regions. Decadal ENSO dominates the SLA in the south tropical IO for both seasons and near the coasts of Sumatra and the Bay during winter. Decadal IOD and monsoon, however, control the coastal SLA during summer. Remote and local winds over the IO are the main drivers for decadal SLA, while the Pacific influence via the ITF is strong mainly in the southeast basin.

Keywords: regional sea level; multi-decadal trend; decadal variability; climate mode; internal variability; external forcing; Indian Ocean

Read: Han, W., Stammer, D., Meehl, G., Hu, A., Sienz, F., & Zhang, L. (2018). Multi-decadal trend and decadal variability of the regional sea level over the Indian Ocean since the 1960s: Roles of climate modes and external forcing. Climate, 6: 51. doi:10.3390/cli6020051.

Online: https://doi.org/doi:10.3390/cli6020051

Date issued: June 2018

Euro-Atlantic winter storminess and precipitation extremes under 1.5 degrees C vs. 2 degrees C warming scenarios

Abstract: Severe winter storms in combination with precipitation extremes pose a serious threat to Europe. Located at the southeastern exit of the North Atlantic's storm track, European coastlines are directly exposed to impacts by high wind speeds, storm floods and coastal erosion. In this study we analyze potential changes in simulated winter storminess and extreme precipitation, which may occur under 1.5 or 2 °C warming scenarios. Here we focus on a first simulation suite of the atmospheric model CAM5 performed within the HAPPI project and evaluate how changes of the horizontal model resolution impact the results regarding atmospheric pressure, storm tracks, wind speed and precipitation extremes.

The comparison of CAM5 simulations with different resolutions indicates that an increased horizontal resolution to 0.25° not only refines regional-scale information but also improves large-scale atmospheric circulation features over the Euro-Atlantic region. The zonal bias in monthly pressure at mean sea level and wind fields, which is typically found in low-resolution models, is considerably reduced. This allows us to analyze potential changes in regional- to local-scale extreme wind speeds and precipitation in a more realistic way.

Our analysis of the future response for the 2 °C warming scenario generally confirms previous model simulations suggesting a poleward shift and intensification of the meridional circulation in the Euro-Atlantic region. Additional analysis suggests that this shift occurs mainly after exceeding the 1.5 °C global warming level, when the midlatitude jet stream manifests a strengthening northeastward. At the same time, this northeastern shift of the storm tracks allows an intensification and northeastern expansion of the Azores high, leading to a tendency of less precipitation across the Bay of Biscay and North Sea.

Regions impacted by the strengthening of the midlatitude jet, such as the northwestern coasts of the British Isles, Scandinavia and the Norwegian Sea, and over the North Atlantic east of Newfoundland, experience an increase in the mean as well as daily and sub-daily precipitation, wind extremes and storminess, suggesting an important influence of increasing storm activity in these regions in response to global warming.

Read: Barcikowska, M. J., Weaver, S. J., Feser, F., Russo, S., Schenk, F., Stone, D. A., Wehner, M. F., & Zahn, M. (2018). Euro-Atlantic winter storminess and precipitation extremes under 1.5 degrees C vs. 2 degrees C warming scenarios. Earth System Dynamics, 9, 679-699. doi:10.5194/esd-9-679-2018.

Online: https://doi.org/doi:10.5194/esd-9-679-2018

Contact: Frauke Feser (frauke.feserdummy@hzgdummy2.de)

Date issued: June 2018

Internal variability in European summer temperatures at 1,5°C and 2°C of global warming

Abstract: We use the 100-member Grand Ensemble with the climate model MPI-ESM to evaluate the controllability of mean and extreme European summer temperatures with the global mean temperature targets in the Paris Agreement. We find that European summer temperatures at 2 °C of global warming are on average 1 °C higher than at 1.5 °C of global warming with respect to pre-industrial levels. In a 2 °C warmer world, one out of every two European summer months would be warmer than ever observed in our current climate. Daily maximum temperature anomalies for extreme events with return periods of up to 500 years reach return levels of 7 °C at 2 °C of global warming and 5.5 °C at 1.5 °C of global warming. The largest differences in return levels for shorter return periods of 20 years are over southern Europe, where we find the highest mean temperature increase. In contrast, for events with return periods of over 100 years these differences are largest over central Europe, where we find the largest changes in temperature variability. However, due to the large effect of internal variability, only four out of every ten summer months in a 2 °C warmer world present mean temperatures that could be distinguishable from those in a 1.5 °C world. The distinguishability between the two climates is largest over southern Europe, while decreasing to around 10% distinguishable months over eastern Europe. Furthermore, we find that 10% of the most extreme and severe summer maximum temperatures in a 2 °C world could be avoided by limiting global warming to 1.5 °C.

Read: Suarez-Gutierrez, L., Li, C., Müller, W. A., & Marotzke, J. (2018). Internal variability in European summer temperatures at 1,5°C and 2°C of global warming. Environmental Research Letters, 13: 064026. doi:10.1088/1748-9326/aaba58.

Date issued: June 2018

Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations

Abstract: For the sediments of the central and southern North Sea different sources of alkalinity generation are quantified by a regional modelling system for the period 2000–2014. For this purpose a formerly global ocean sediment model coupled with a pelagic ecosystem model is adapted to shelf sea dynamics, where much larger turnover rates than in the open and deep ocean occur. To track alkalinity changes due to different nitrogen-related processes, the open ocean sediment model was extended by the state variables particulate organic nitrogen (PON) and ammonium. Directly measured alkalinity fluxes and those derived from Ra isotope flux observation from the sediment into the pelagic are reproduced by the model system, but calcite building and calcite dissolution are underestimated. Both fluxes cancel out in terms of alkalinity generation and consumption. Other simulated processes altering alkalinity in the sediment, like net sulfate reduction, denitrification, nitrification, and aerobic degradation, are quantified and compare well with corresponding fluxes derived from observations. Most of these fluxes exhibit a strong positive gradient from the open North Sea to the coast, where large rivers drain nutrients and organic matter. Atmospheric nitrogen deposition also shows a positive gradient from the open sea towards land and supports alkalinity generation in the sediments. An additional source of spatial variability is introduced by the use of a 3-D heterogenous porosity field. Due to realistic porosity variations (0.3–0.5) the alkalinity fluxes vary by about 4 %. The strongest impact on interannual variations of alkalinity fluxes is exhibited by the temporal varying nitrogen inputs from large rivers directly governing the nitrate concentrations in the coastal bottom water, thus providing nitrate necessary for benthic denitrification. Over the time investigated the alkalinity effluxes decrease due to the decrease in the nitrogen supply by the rivers.

Read: Pätsch, J., Kühn, W., & Six, K. D. (2018). Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations. Biogeosciences, 15, 3293-3309. doi:10.5194/bg-15-3293-2018.

Online: https://doi.org/10.5194/bg-15-3293-2018

Date issued: May 2018

A model-based projection of historical state of a coastal ecosystem: Relevance of phytoplankton stoichiometry

Abstract: We employed a coupled physical-biogeochemical modelling framework for the reconstruction of the historic (H), pre-industrial state of a coastal system, the German Bight (southeastern North Sea), and we investigated its differences with the recent, control (C) state of the system. According to our findings: i) average winter concentrations of dissolved inorganic nitrogen and phosphorus (DIN and DIP) concentrations at the surface are 7090% and 5070% lower in the H state than in the C state within the nearshore waters, and differences gradually diminish towards off-shore waters; ii) differences in average growing season chlorophyll a (Chl) concentrations at the surface between the two states are mostly less than 50%; iii) in the off-shore areas, Chl concentrations in the deeper layers are affected less than in the surface layers; iv) reductions in phytoplankton carbon (C) biomass under the H state are weaker than those in Chl, due to the generally lower Chl:C ratios; v) in some areas the differences in growth rates between the two states are negligible, due to the compensation by lower light limitation under the H state, which in turn explains the lower Chl:C ratios; vi) zooplankton biomass, and hence the grazing pressure on phytoplankton is lower under the H state. This trophic decoupling is caused by the low nutritional quality (i.e., low N:C and P:C) of phytoplankton. These results call for increased attention to the relevance of the acclimation capacity and stoichiometric flexibility of phytoplankton for the prediction of their response to environmental change.

Keywords: Eutrophication; Pristine conditions; Reconstruction; Adaptation; Acclimation

Read: Kerimoglu, O., Große, F., Kreus, M., Lenhart, H.-J., & van Beusekom, J. (2018). A model-based projection of historical state of a coastal ecosystem: Relevance of phytoplankton stoichiometry. Science of the Total Environment, 639, 1311-1323. doi:10.1016/j.scitotenv.2018.05.215.

Online: https://doi.org/10.1016/j.scitotenv.2018.05.215

Contact: Justus van Beusekom (justus.van.beusekomdummy@hzgdummy2.de)

Date issued: May 2018

Application of Thermal and Phenological Land Surface Parameters for Improving Ecological Niche Models of Betula utilis in the Himalayan Region

Abstract: Modelling ecological niches across vast distribution ranges in remote, high mountain regions like the Himalayas faces several data limitations, in particular nonavailability of species occurrence data and fine-scale environmental information of sufficiently high quality. Remotely sensed data provide key advantages such as frequent, complete, and long-term observations of land surface parameters with full spatial coverage. The objective of this study is to evaluate modelled climate data as well as remotely sensed data for modelling the ecological niche of Betula utilis in the subalpine and alpine belts of the Himalayan region covering the entire Himalayan arc. Using generalized linear models (GLM), we aim at testing factors controlling the species distribution under current climate conditions. We evaluate the additional predictive capacity of remotely sensed variables, namely remotely sensed topography and vegetation phenology data (phenological traits), as well as the capability to substitute bioclimatic variables from downscaled numerical models by remotely sensed annual land surface temperature parameters. The best performing model utilized bioclimatic variables, topography, and phenological traits, and explained over 69% of variance, while models exclusively based on remotely sensed data reached 65% of explained variance. In summary, models based on bioclimatic variables and topography combined with phenological traits led to a refined prediction of the current niche of B. utilis, whereas models using solely climate data consistently resulted in overpredictions. Our results suggest that remotely sensed phenological traits can be applied beneficially as supplements to improve model accuracy and to refine the prediction of the species niche. We conclude that the combination of remotely sensed land surface temperature parameters is promising, in particular in regions where sufficient fine-scale climate data are not available.

Keywords: Betula utilis; Chelsa; ecological niche model; Enhanced Vegetation Index; Himalaya; MODIS (Moderate-resolution Imaging Spectroradiometer) Land Cover Dynamics; MODIS Land Surface Temperature; plant phenology; remote sensing; treeline ecotone

Read: Bobrowski, M., Bechtel, B., Böhner, J., Oldeland, J., Weidinger, J., & Schickhoff, U. (2018). Application of Thermal and Phenological Land Surface Parameters for Improving Ecological Niche Models of Betula utilis in the Himalayan Region. Remote Sensing, 10(6): 814, pp. 1-19. doi:10.3390/rs10060814.

Online: https://doi.org/10.3390/rs10060814

Contact: Benjamin Bechtel (benjamin.bechteldummy@uni-hamburgdummy2.de)

Date issued: May 2018

A well-balanced meshless tsunami propagation and inundation model

Abstract: We present a novel meshless tsunami propagation and inundation model. We discretize the nonlinear shallow-water equations using a well-balanced scheme relying on radial basis function based finite differences. The inundation model relies on radial basis function generated extrapolation from the wet points closest to the wet-dry interface into the dry region. Numerical results against standard one- and two-dimensional benchmarks are presented.

Read: Brecht, R., Bihlo, A., MacLachlan, S., & Behrens, J. (2018). A well-balanced meshless tsunami propagation and inundation model. Advances in Water Resources, 115, 273-285. doi:10.1016/j.advwatres.2017.12.013.

Online: https://doi.org/10.1016/j.advwatres.2017.12.013

Date issued: April 2018

Enhanced Modeling of Annual Temperature Cycles with Temporally Discrete Remotely Sensed Thermal Observations

Abstract: Satellite thermal remote sensing provides land surface temperatures (LST) over extensive areas that are vital in various applications, but this technique suffers from its sampling style and the impenetrability of clouds, which frequently generates data gaps. Annual temperature cycle (ATC) models can fill these gaps and estimate continuous daily LST dynamics from a number of thermal observations. However, the standard ATC model (termed ATCS) remains incapable of quantifying the short-term LST variations caused by synoptic conditions. By incorporating in-situ surface air temperatures (SATs) and satellite-derived normalized difference vegetation indexes (NDVIs), here we proposed an enhanced ATC model (ATCE) to describe the daily LST fluctuations. With Aqua/MODIS LST products as validation data, we implemented and tested the ATCE over the Yangtze River Delta region of China. The results demonstrate that, when compared with the ATCS, the overall root mean square errors of the ATCE decrease by 1.0 and 0.8 K for the day and night, respectively. The accuracy improvements vary with land cover types with greater improvements over the forest, grassland, and built-up areas than over cropland and wetland. The assessments at different time scales further confirm that LST fluctuations can be better described by the ATCE. Though with limitations, we consider this new model and its associated parameters hold great potentials in various applications.

Keywords: thermal remote sensing; land surface temperature; annual temperature cycle; LST dynamics; MODIS

Read: Zou, Z., Zhan, W., Liu, Z., Bechtel, B., Gao, L., Hong, F., Huang, F., & Lai, J. (2018). Enhanced Modeling of Annual Temperature Cycles with Temporally Discrete Remotely Sensed Thermal Observations. Remote Sensing, 10(4): 650, pp. 1-12. doi:10.3390/rs10040650.

Date issued: April 2018

Deforestation for agricultural expansion in SW Zambia and NE Namibia and the impacts on soil fertility, soil organic carbon- and nutrient levels

Abstract: In southern African drylands, an important driver of deforestation is the ongoing conversion of woodland to smallholder agriculture. Our study in NE Namibia and SW Zambia evaluated the potential of operational earth observation satellites to characterize land-use change processes and quantifi ed their impact on soil organic carbon (SOC) and nutrient concentrations. We found that the area under agricultural use increased by 24% from 2002 to 2013, mainly at the expense of natural vegetation (i.e., woodland). This conversion caused a decline in SOC and total N and tended to increase plant-available P in the soils of old agricultural fields. The eff ects were most pronounced in NE Namibia, where the total SOC stocks were 19.6% (±18.4 SD) lower in agricultural land compared to woodland. Moreover, the losses in SOC and total N tended to result in a decline of predicted maize yields calculated with the QUEFTS model by ~15% when comparing soils of old agricultural fi elds and woodland. Overall, our results indicate that long-term continuation of low-input arable farming can reduce soil fertility.

Read: De Blécourt, M., Röder, A., Gröngröft, A., Baumann, S., Frantz, D., & Eschenbach, A. (2018). Deforestation for agricultural expansion in SW Zambia and NE Namibia and the impacts on soil fertility, soil organic carbon- and nutrient levels. In R. Revermann, K. M. Krewenka, U. Schmiedel, J. M. Olwoch, J. Helmschrot, & N. Jürgens (Eds.),  Climate change and adaptive land management in southern Africa: assessments, changes, challenges, and solutions: product of the first research portfolio of SASSCAL 2012-2018 (pp. 242-250). Göttingen; Windhoek: Klaus Hess Verlag.

Online: https://doi.org/10.7809/b-e.00330

Contact: Annette Eschenbach (a.eschenbachdummy@ifb.uni-hamburgdummy2.de)

Date issued: April 2018

Acacia trees modify soil water dynamics and the potential groundwater recharge in savanna ecosystems

Abstract: The eff ect of increasing tree density on groundwater resources of semiarid landscapes is a topic of controversy. Since 2007, we have registered the soil water dynamics with fi eld monitoring techniques on a commercial rangeland farm in the central Namibian thorn-bush savanna. Monitoring profi les are located below Acacia mellifera canopies, in the intercanopy area, and on a de-bushed grassland. Here we demonstrate (1) an increase in soil moisture larger than precipitation at some rain events, interpreted as water run-on resulting from surface ponding; (2) an overall reduction in water infi ltration in the below-canopy area of A. mellifera compared to the intercanopy space; and (3) a faster drying of the soil in the below-canopy space because of root water uptake. These processes resulted in a potential for deep drainage about threefold larger in the intercanopy space than in the area below the canopy. Thus, increasing bush encroachment is likely to reduce groundwater recharge and should be validated by an interdisciplinary analysis of hydrogeologists, soil scientists, botanists, and farm managers.

Read: Gröngröft, A., De Blécourt, M., Landschreiber, L., Classen, N., & Eschenbach, A. (2018). Acacia trees modify soil water dynamics and the potential groundwater recharge in savanna ecosystems. In R. Revermann, K. M. Krewenka, U. Schmiedel, J. M. Olwoch, J. Helmschrot, & N. Jürgens (Eds.), Climate change and adaptive land management in southern Africa: assessments, changes, challenges, and solutions: product of the first research portfolio of SASSCAL 2012-2018 (pp. 177-186). Göttingen; Windhoek: Klaus Hess Verlag.

Online: https://doi.org/10.7809/b-e.00321

Contact: Annette Eschenbach (a.eschenbachdummy@ifb.uni-hamburgdummy2.de)

Date issued: April 2018

Web-Based Interactive Visualization Of A High Resolution Global Lithological Map

Abstract: The Lithological Map Viewer is a tool to study the distribution of mapped lithological units, and which allows to zoom into areas of interest. The underlying data is based on globally high resolution information, derived from the Global Lithological Map database GLiM v1.1. That database presents by now the most accurate globally available picture of the lithological characteristics of the Earth’s crust beneath the soil. Rock type information from more than 90 regional maps and additional literature sources was translated into 16 lithological classes and numerous subclasses. The map database has been used by various disciplines ranging from geochemistry over hydrology to ecology. New techniques have been used to make this information available in an easy to use fashion for spatial, visual analysis. Built upon the emerging graphics language WebGL, the Lithological Map Viewer has the advantage of being seamlessly integrated into standard Web browsers, eliminating the need to install additional plugins before data viewing. Moreover, WebGL offers the possibility of graphics hardware accelerated data rendering. The high resolution of the global lithological map translates to a considerable amount of data: over 200 million points were stored for our visualization in a point cloud format. In order to achieve the interactive rendering of millions of points in a web browser, a visualization strategy was adopted that decreases the rendered data volume while increasing rendering and data transfer speed at the same time. Thus, the data set was pre-partitioned spatially with the help of an out-of-core algorithm that stores various levels of detail of the original model in a hierarchical octree data structure. We combined this data structure with a view-dependent rendering technique based on the principle that the greater the distance from the viewing point, the fewer details will need to be displayed. Future directions: The Lithological Map Viewer can be extended to enable data visualization for other Earth Science domains, such as oceanography, hydrology, meteorology or climate science.

Read: Brisc, F., Hartmann, J., & Moosdorf, N. (2018). Web-Based Interactive Visualization Of A High Resolution Global Lithological Map. Geophysical Research Abstracts, 20: 15042. Retrieved from meetingorganizer.copernicus.org/EGU2018/EGU2018-15042.pdf.

Online: https://meetingorganizer.copernicus.org/EGU2018/orals/28030

Date issued: April 2018

Time series analysis of moderate resolution land surface temperatures

Abstract: Chapter 5 of the book ‘Remote Sensing Time Series Image Processing’ investigates land surface temperature (LST), a highly dynamic parameter that drives many terrestrial physical processes. However, the analysis of satellite LST is complicated due to cloud gaps and the pronounced spatiotemporal variability of LST. A prominent way to overcome these limitations is to model the annual LST cycle (ATC) through time series analysis by deriving annual cycle parameters (ACP). This chapter presents the ACP derived from MODIS collection-6 LST data for Europe and North Africa and introduces a new parameter, the coefficient of determination. Among the large number of potential applications, examples of ACP-based SUHI analysis and LST downscaling are presented.

Read: Bechtel, B., & Sismanidis, P. (2018). Time series analysis of moderate resolution land surface temperatures. In Q. Weng (Ed.), Remote Sensing: Time Series Image Processing. Taylor & Francis.

Online: https://www.researchgate.net/publication/324823071_Time_Series_Analysis_of_Moderate_Resolution_Land_Surface_Temperatures

Contact: Benjamin Bechtel (benjamin.bechteldummy@uni-hamburgdummy2.de)

Date issued: March 2018

Climate change effects on crop productivity and welfare sensitivity analysis for smallholder farmers in Malawi

Abstract: The effects of climate change on smallholder agriculture under different crop technologies, namely conservation agriculture, Falbedia albida, optimal fertilisation and intensive farming, were analysed against the conventional subsistence farming in Malawi. A biophysical economic modelling approach was used over a 60-year period to assess changes in crop productivity, total welfare and land-use options. The results indicate varying decreases in crop yield. For instance, when compared to the crop yield in 2010, maize yield decreased by -20% under subsistence farming and -0.1% under intensive farming in the seventh decade (2061 to 2070). Adaptation to climate change effects increased total welfare by 24% and producer revenues by 44% when compared to no adaptation. To optimise the welfare of smallholder farmers in Malawi, the study recommends increasing the adoption of intensive farming, conservation agriculture and Falbedia albida to at least 9.5%, 12% and 10% of total cultivated area in the 7th decade respectively. The study also reveals that farmers’ inability to optimise land use has a higher negative impact on welfare when compared to the effect from climate change. This means that the optimisation of crop and technology choices may play a more vital role in improving farmers’ welfare than mere adaptation to climate change.

Read: Kachulu, M. (2018). Climate change effects on crop productivity and welfare sensitivity analysis for smallholder farmers in Malawi. African Journal of Agricultural and Resource Economics, 13, 58-77.

Date issued: March 2018

Terrestrische und semiterrestrische Ökosysteme

Abstract: Die Metropolregion Hamburg (MRH) erstreckt sich auf einer Gesamtfläche von ca. 26.000 km2 über insgesamt 19 (Land-)Kreise/kreisfreie Städte in den Bundesländern Hamburg, Schleswig-Holstein, Mecklenburg-Vorpommern und Niedersachsen. Entsprechend vielgestaltig sind die naturräumlichen Verhältnisse, die im Hinblick auf die Landschaftsentwicklung maßgeblich durch die quartären Vereisungen geprägt sind. Das Klima der MRH lässt sich in ein stärker ozeanisch geprägtes in Küstennähe und in ein weniger ozeanisch geprägtes der südöstlichen Teilgebiete differenzieren. Die Zunahme kontinentaler Klimaeinflüsse entlang eines von Nordwest nach Südost verlaufenden Gradienten kommt u. a. in einer um 0,4 °C ansteigenden Jahresmitteltemperatur und einer von 831 mm/Jahr (Station Cuxhaven) auf 557 mm/Jahr (Station Lüchow) zurückgehenden Niederschlagsmenge zum Ausdruck.

Read: Schickhoff U, Eschenbach A (2018) Terrestrische und semiterrestrische Ökosysteme. In: Storch H, Meinke I, Claußen M (eds.) Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg und Norddeutschland. Springer Spektrum. Kapitel 6. S. 111-145 doi:10.1007/978-3-662-55379-4_6.

Online: https://doi.org/10.1007/978-3-662-55379-4_6

Date issued: March 2018

Enhanced dewatering optimizes compactibility of processed dredged material

Abstract: Purpose: The utilization of dredged material in dike construction as a substitute for traditionally used aged marsh sediment is considered an advisable option with respect to ecological as well as economic aspects. As a prerequisite to the application, the equivalency with respect to soil physical and mechanical properties of the materials has to be verified. Previous investigations on the compactibility of dredged materials used for dike construction had shown that the bulk densities of these materials were considerably lower than bulk densities of aged marsh sediments. The aim of the investigations presented in this paper was to analyze whether the compactibility of the processed dredged material could be improved by enhanced dewatering of the material prior to construction. It was hypothesized that a decreased water content of the material would allow higher bulk densities to be achieved during construction and hence the soil physical properties would become more comparable to those of the aged marsh sediments. Materials and methods: To examine whether the compactibility of dredged material can be enhanced by pre-drying, Proctor tests were carried out at different initial water contents. Moreover, it was examined whether the temperature of oven-drying at 30 and 105 °C affects the compactibility of these materials and whether ripening, i.e., the repeated drying and wetting of the dredged material under natural and laboratory conditions, can improve their compactibility. Results and discussion: The investigations on the effect of the various further processing methods showed that the compactibility and therefore the suitability of processed dredged material for dike construction can be improved by air-drying. A linear relationship between dehydration and Proctor density was found. Air-drying to water contents of 10% dry weight (DW) resulted in an improvement of the Proctor density of up to 11%. However, the tests on the effect of the drying temperature on the compactibility showed that oven-drying had no additional effect on the compactibility of the dredged materials. Ripening under laboratory and natural conditions did not lead to statistically significant changes in the compactibility of the processed dredged material either. Conclusions: Air-drying of processed dredged material to water contents less than 10% DW is considered to be a useful pre-treatment option to improve the compaction behavior of processed dredged material and to obtain a better functional equivalency with traditionally used dike construction materials such as fine-grained aged marsh sediments.

Keywords: Aged marsh sediments; Air-drying; Compactibility; Oven-drying; Processed dredged material; Ripening 

Read: Oing, K., Gröngröft, A., & Eschenbach, A. (2018). Enhanced dewatering optimizes compactibility of processed dredged material. Journal of Soils and Sediments, 1-11. doi:10.1007/s11368-018-1958-7.

Online: https://doi.org/10.1007/s11368-018-1958-7

Contact: Annette Eschenbach (a.eschenbachdummy@ifb.uni-hamburgdummy2.de)

Date issued: February 2018

Compiling and Mapping Global Permeability of the Unconsolidated and Consolidated Earth: GLobal HYdrogeology MaPS 2.0 (GLHYMPS 2.0)

Abstract: The spatial distribution of subsurface parameters such as permeability are increasingly relevant for regional to global climate, land surface, and hydrologic models that are integrating groundwater dynamics and interactions. Despite the large fraction of unconsolidated sediments on Earth's surface with a wide range of permeability values, current global, high‐resolution permeability maps distinguish solely fine‐grained and coarse‐grained unconsolidated sediments. Representative permeability values are derived for a wide variety of unconsolidated sediments and applied to a new global map of unconsolidated sediments to produce the first geologically constrained, two‐layer global map of shallower and deeper permeability. The new mean logarithmic permeability of the Earth's surface is −12.7 ± 1.7 m2 being 1 order of magnitude higher than that derived from previous maps, which is consistent with the dominance of the coarser sediments. The new data set will benefit a variety of scientific applications including the next generation of climate, land surface, and hydrology models at regional to global scales.

Keywords: permeability; global hydrology models; data synthesis; global map

Read: Huscroft, J., Gleeson, T., Hartmann, J., & Börker, J. (2018). Compiling and mapping global permeability of the unconsolidated and consolidated Earth: GLobal HYdrogeology MaPS 2.0 (GLHYMPS 2.0). Geophysical Research Letters, 45, 1897–1904, doi:10.1002/2017GL075860.

Online: https://doi.org/10.1002/2017GL075860

Date issued: 2018

Der ökonomische Wert von Klimainformation: Zur Neuinterpretation von Klimazielen unter antizipiertem Lernen

Abstract: How much would a rational decision maker be willing to invest in the reduction of uncertainty of climate projections by an order of magnitude? This seemingly technical question requires shedding some light on the foundations of the two leading schools of thought within climate economics: cost benefit and cost effectiveness analysis. While the former takes off from the most solid axiomatic basis, its results are currently not robust regarding some hard to determine input parameters. The latter operationalizes politically decided environmental targets that can be interpreted as an expression of strong sustainability. The 2°C target is of that sort. However under anticipated future learning fundamental conceptual difficulties appear within an interpretation as a hard limit. We offer a new, softer interpretation of the 2°C target that avoids these difficulties. Among other advantages of this new interpretation the question about the expected economic value of the reduction of climate response uncertainty regarding greenhouse gas emissions becomes a well-posed one. Perfect learning in that regard could on average save up to hundreds of billions of Euros per year if a stringent 2°C policy were pursued. It remains to be shown whether our softer interpretation is the only interpretation of a target that would be consistent with learning, or whether a third way between the traditional “hard” and our “soft” interpretation were possible.

Keywords: Unsicherheit; Risiko; Standardansatz; Vorsorgeansatz; Kosten-Nutzen-Analyse; Kosten-Effektivitäts-Analyse; Kosten-Risiko-Analyse; Klimapolitik

Read: Held, H. (2018). Der ökonomische Wert von Klimainformation: Zur Neuinterpretation von Klimazielen unter antizipiertem Lernen. In N. Janich, & L. Rhein (Eds.), Unsicherheit als Herausforderung für die Wissenschaft: Reflexionen aus Natur-, Sozial- und Geisteswissenschaften. Frankfurt a.M.: Peter Lang.

Online: https://www.peterlang.com/view/9783631761533/chapter-003.xhtml#_idTextAnchor058

Date issued: 2018

Wissen, Nichtwissen, Unwissen, Unsicherheit: Zur Operationalisierung und Auswertung von Wissensitems am Beispiel des Klimawissens

Abstract: Science is present in all dimensions of laypeople’s everyday lives and serves as a basis for decisions. However, scientific topics such as climate change are very complex, abstract and uncertain – thus for laypeople difficult to understand. Mass media act as significant mediators between science and lay audiences. Much empirical research exists about the relations between media use and knowledge as well as attitudes towards science. Nonetheless, statistical proof for these correlations is often missing. A main reason for that can be seen in insufficient theoretical examinations of ‚knowledge‘ and measurement problems. This article tries to address these issues by focusing on how knowledge can be conceptualised and operationalised in empirical studies. Five different dimensions of knowledge about climate change are discussed: knowledge about (1) causes, (2) basics and (3) effects of climate change as well as (4) climate-friendly behavior and (5) the procedures of the climate sciences. Different theoretical concepts of knowledge, ignorance and misinformation in combination with the dimension of (un)certainty/confidence are introduced. Using empirical data from an online survey about climate change, the consequences of different response formats and scales are illustrated and discussed.

Keywords: Klimawissen; Klimaskepsis; Nichtwissen; Unwissen; empirische Operationalisierung; Internetnutzung; Medienrezeption

Read: Hoppe, I., Reif, A., & Taddicken, M. (2018). Wissen, Nichtwissen, Unwissen, Unsicherheit: Zur Operationalisierung und Auswertung von Wissensitems am Beispiel des Klimawissens. In N. Janich, & L. Rhein (Eds.), Unsicherheit als Herausforderung für die Wissenschaft: Reflexionen aus Natur-, Sozial- und Geisteswissenschaften. Frankfurt a.M.: Peter Lang.

Online: https://www.peterlang.com/view/9783631761533/chapter-007.xhtml

Date issued: May 2018

Global climate control on carbonate weathering intensity

Abstract: Carbonate rocks are a peculiarity of the Earth relative to other planets in the solar system. Large terrestrial areas are covered by carbonate lithology, which actively reacts with atmospheric/biospheric CO2. Although carbonate rocks represent a major component of the global carbon cycle, their intensity and rates of chemical weathering have been overlooked. In this study, we examine three global databases of rivers and springs draining carbonate regions under various climate conditions (from −15 °C to +30 °C). Using Ca²⁺ + Mg²⁺ concentrations as a proxy, we show that carbonate weathering intensity depends upon land temperature according to a boomerang-type relationship, with maximum dissolution between 10 and 15 °C. We show that this pattern is primarily controlled by thermodynamics if we assume that the partial pressure of CO2 in soil (pCO2) increases from atmospheric-like levels under cold climate up to 100 times the present day atmospheric concentration under hot climate. The link between soil pCO2 and land temperature is still not very well known, but by using three different published predictive soil pCO2 vs. T curves, we show that the boomerang shape can be, at least qualitatively, reproduced. This study shows that more data on carbonate weathering in various environments are needed to predict with more accuracy the role that carbonate lithologies and overlying ecosystems could play in the Anthropocene.

Keywords: Carbonate, Weathering, pCO2, Climate, Global, Ecosystem

Read: Gaillardet, J., Calmels, D., Romero-Mujalli, G., Zakharova, E., & Hartmann, J. (2018). Global climate control on carbonate weathering intensity. Chemical Geology, ahead of print, available online. doi:10.1016/j.chemgeo.2018.05.009.

Online: https://doi.org/10.1016/j.chemgeo.2018.05.009

Date issued: May 2018

A structure-preserving split finite element discretization of the split wave equations

Abstract: We introduce a new finite element (FE) discretization framework applicable for covariant split equations. The introduction of additional differential forms (DF) that form pairs with the original ones permits the splitting of the equations into topological momentum and continuity equations and metric-dependent closure equations that apply the Hodge-star operator. Our discretization framework conserves this geometrical structure and provides for all DFs proper FE spaces such that the differential operators (here gradient and divergence) hold in strong form. We introduce lowest possible order discretizations of the split 1D wave equations, in which the discrete momentum and continuity equations follow by trivial projections onto piecewise constant FE spaces, omitting partial integrations. Approximating the Hodge-star by nontrivial Galerkin projections (GP), the two discrete metric equations follow by projections onto either the piecewise constant (GP0) or piecewise linear (GP1) space. Out of the four possible realizations, our framework gives us three schemes with significantly different behavior. The split scheme using twice GP1 is unstable and shares the dispersion relation with the P1–P1 FE scheme that approximates both variables by piecewise linear spaces (P1). The split schemes that apply a mixture of GP1 and GP0 share the dispersion relation with the stable P1–P0 FE scheme that applies piecewise linear and piecewise constant (P0) spaces. However, the split schemes exhibit second order convergence for both quantities of interest. For the split scheme applying twice GP0, we are not aware of a corresponding standard formulation to compare with. Though it does not provide a satisfactory approximation of the dispersion relation as short waves are propagated much too fast, the discovery of the new scheme illustrates the potential of our discretization framework as a toolbox to study and find FE schemes by new combinations of FE spaces.

Keywords: plit linear wave equations, Split finite element method, Dispersion relation, Structure-preserving discretization, Shallow-water wave equations

Read: Bauer, W., & Behrens, J. (2018). A structure-preserving split finite element discretization of the split wave equations. Applied Mathematics and Computation, 325, 375-400. doi:10.1016/j.amc.2017.12.035.

Online: https://doi.org/10.1016/j.amc.2017.12.035

Issued: May 2018

Sustainability assessment of electricity generation technologies in Egypt using multi-criteria decision analysis

Abstract: Future electricity planning necessitates a thorough multi-faceted analysis of the available technologies in order to secure the energy supply for coming generations. To cope with worldwide concerns over sustainable development and meet the growing demands of electricity we assess the future potential technologies in Egypt through covering their technical, economic, environmental and social aspects. In this study we fill the gap of a lacking sustainability assessment of energy systems in Egypt where most of the studies focus mainly on the economic and technical aspects of planning future installation of power plants in Egypt. Furthermore, we include the stakeholder preferences of the indicators in the energy sector into our assessment. Moreover, we perform a sensitivity analysis through single dimension assessment scenarios of the technologies as well as a sustainable scenario with equal preferences of all dimensions of the sustainability. We employ two multi-criteria decision analysis (MCDA) methodologies: the analytical hierarchy process for weighing the assessment criteria, and the weighted sum method for generating a general integrated sustainability index for each technology. The study investigates seven technologies: coal, natural gas, wind, concentrated solar power, photovoltaics, biomass and nuclear. The results reveal a perfect matching between the ranking of the technologies by the stakeholders and the sustainable scenario showing the highest ranking for natural gas and the lowest for nuclear and coal. There is a strong potential for renewable energy technologies to invade the electricity market in Egypt where they achieve the second ranking after natural gas. The Monte-Carlo approach gives photovoltaics a higher ranking over concentrated solar power as compared to the sample data ranking. The study concludes the importance of a multi-dimensional evaluation of the technologies while considering the preferences of the stakeholders in order to achieve a reliable and sustainable future energy supply.

Keywords: sustainability, electricity, technology assessment, MCDA, Egypt

Read: Shaaban, M., Scheffran, J., Böhner, J., & Elsobki, M. S. (2018). Sustainability assessment of electricity generation technologies in Egypt using multi-criteria decision analysis. Energies, 11: 1117. doi:10.3390/en11051117.

Online: https://doi.org/10.3390/en11051117

Date issued May 2018

Climate Change-Induced Shift of Tree Growth Sensitivity at a Central Himalayan Treeline Ecotone

Abstract: Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth–climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions during pre-monsoon seasons. The aim of this study was to analyze growth–climate relationships for more than a century for a treeline ecotone in east-central Nepal and to test for Blue Intensity (BI; used as a surrogate of maximum late wood density) as climate proxy. We determined the relationships of Abies spectabilis radial tree growth and BI to climate by correlating both to temperature, precipitation and drought index data. The results showed a significantly unstable dendroclimatic signal over time. Climate warming-induced moisture deficits during pre-monsoon seasons became a major factor limiting radial tree growth during recent decades. Earlier in time, the dendroclimatic signal was weaker, predominantly reflecting a positive relationship of tree growth and summer temperature. Compared to radial tree growth, BI showed a different but strong climate signal. Temporally unstable correlations may be attributed to increasing effects of above-average rates of climate warming. An extended network of Himalayan tree-ring sites is needed to further analyze cause–effect relationships and to solve this attribution problem.

Keywords: Blue Intensity, climate warming, Himalayan Silver Fir (Abies spectabilis), Nepal Himalaya, temporal dynamics, tree growth–climate correlation, treeline ecotone, tree-ring width

Read: Schwab, N.; Kaczka, R.J.; Janecka, K.; Böhner, J.; Chaudhary, R.P.; Scholten, T.; Schickhoff, U. (2018). Climate Change-Induced Shift of Tree Growth Sensitivity at a Central Himalayan Treeline Ecotone. Forests, 9: 267. doi:10.3390/f9050267

Online: https://doi.org/10.3390/f9050267

Date issued May 2018

The Hamburg Tornado (7 June 2016) from the perspective of low-cost high-resolution radar data and weather forecast model

Abstract: A tornado hit the northeastern suburbs of Hamburg, Germany, on 7 June 2016. It had an estimated strength of upper end F1 on the Fujita scale and was short-lived with an approximate duration of only 13 min and a path length of just about 1.3 km. We demonstrate that such a small-scale, extreme event can be observed and forecasted accurately by a low-cost radar and by an atmospheric model with low computational costs, respectively. Observations from a low-cost single polarized X-band radar covering the urban area of Hamburg with 60 m spatial and 30 s temporal resolution are analyzed with respect to their ability to capture the development as well as the track of the tornado. In contrast to the national C-band radar network, the X-band radar is capable of capturing the hook echo of the tornado as well as the circular pattern in rain rates, because of its higher resolution in space and time. High-resolution forecasts of the tornado event are conducted with the computational efficient Conformal Cubic Atmosphere Model (CCAM) in order to test the capability of predicting the tornado with a lead time of a few hours. A three step downscaling method is used to obtain a spatial resolution of 1 km with initial conditions taken from the NCEP analysis. Calculated severe weather indices clearly indicate a potential for a tornado. CCAM cannot explicitly resolve small scale tornadic features but the model simulates a strong convective cell only a few kilometers apart from the tornadic thunderstorm observed by the radar.

Keywords: Tornado, Weather forecast, X-band radar, Numerical modelling, CCAM

Read: Hoffmann, P., Merker, C., Lengfeld, K., & Ament, F. (2018). The Hamburg Tornado (7 June 2016) from the perspective of low-cost high-resolution radar data and weather forecast model. Atmospheric Research, 211, 1-11. doi:10.1016/j.atmosres.2018.04.009.

Online: https://doi.org/10.1016/j.atmosres.2018.04.009

Date issued: April 2018

Cooperation and Co-Existence Between Farmers and Herders in the Midst of Violent Farmer-Herder Conflicts in Ghana

Abstract: Despite periodic violent conflict between farmers and Fulani herders in many parts of Ghana, cooperative relations between them remain strong. They are “cultural neighbors” who cooperate both in times of violent conflict and during periods of no conflict. Cooperation between them is expressed through everyday interactions, cattle entrustment, resource sharing, trade, friendship, intermarriages, visitations, exchanges, communal labor, and social solidarity. Borrowing from theorizations of cultural neighborhood and everyday peace, this paper uses specific case studies from Northern and Southern Ghana to illustrate the enactment of cooperation between herders and farmers in areas of violent farmer-herder conflict.

Read: Bukari, K. N., Sow, P., & Scheffran, J. (2018). Cooperation and Co-Existence Between Farmers and Herders in the Midst of Violent Farmer-Herder Conflicts in Ghana. African Studies Review, 1-25. doi:10.1017/asr.2017.124.

Online: https://doi.org/10.1017/asr.2017.124

Contact: Jürgen Scheffran (juergen.scheffrandummy@uni-hamburgdummy2.de)

Date issued: April 2018

An Agent-Based Modeling Framework for Simulating Human Exposure to Environmental Stresses in Urban Areas

Abstract: Several approaches have been used to assess potential human exposure to environmental stresses and achieve optimal results under various conditions, such as for example, for different scales, groups of people, or points in time. A thorough literature review in this paper identifies the research gap regarding modeling approaches for assessing human exposure to environment stressors, and it indicates that microsimulation tools are becoming increasingly important in human exposure assessments of urban environments, in which each person is simulated individually and continuously. The paper further describes an agent-based model (ABM) framework that can dynamically simulate human exposure levels, along with their daily activities, in urban areas that are characterized by environmental stresses such as air pollution and heat stress. Within the framework, decision-making processes can be included for each individual based on rule-based behavior in order to achieve goals under changing environmental conditions. The ideas described in this paper are implemented in a free and open source NetLogo platform. A basic modeling scenario of the ABM framework in Hamburg, Germany, demonstrates its utility in various urban environments and individual activity patterns, as well as its portability to other models, programs, and frameworks. The prototype model can potentially be extended to support environmental incidence management through exploring the daily routines of different groups of citizens, and comparing the effectiveness of different strategies. Further research is needed to fully develop an operational version of the model.

Keywords: environmental stress, human exposure, agent-based model, air pollution, urban heat wave, exposure modeling, climate change

Read: Yang, L., Scheffran, J., Hoffmann, P., Rühe, S., Fischereit, J., & Gasser, I. (2018). An Agent-Based Modeling Framework for Simulating Human Exposure to Environmental Stresses in Urban Areas. Urban Science, 2(36), 1-21. doi:10.3390/urbansci2020036.

Online: http://doi.org/10.3390/urbansci2020036

Contact: Jürgen Scheffran (juergen.scheffrandummy@uni-hamburgdummy2.de)

Date issued: April 2018

Assessing the economic impacts of pesticide regulations

Abstract: Economic impacts of pesticide regulations are assessed using five alternative methodologies. The regulations include crop supply-enhancing eradication programs and crop supply-decreasing pesticide bans. Alternative assessment methodologies differ regarding assumptions about market price and crop acreage adjustments. Results show that market and producer adjustments substantially impact conclusions about winners and losers from regulations, and estimated welfare effects can differ widely between the different methodologies. For small technological changes such as the hypothetical pendimethalin regulation, farm budgeting and sector modeling yield similar estimates. For more severe technological changes—like the boll weevil eradication program—simple budgeting approaches lead to a substantial bias.

Keywords: pest control, pesticide ban, insect eradication, farm income, agricultural sector analysis

Read: Schneider, U., Rasche, L., & McCarl, B. (2018). Assessing the economic impacts of pesticide regulations. Agriculture (Switzerland), 8. doi:10.3390/agriculture8040053.

Online: https://doi.org/10.3390/agriculture8040053

Date issued: March 2018

On the role of convective available potential energy (CAPE) in tropical cyclone intensification

Abstract: This study addresses the role of convective available potential energy (CAPE) in the intensification of simulated tropical cyclones. Additionally, it also examines the ‘wind-induced surface heat exchange’ (WISHE) theory in which CAPE is non-existent during intensification. We use a hierarchy of models with different complexity. A low-order tropical cyclone model forms the simplest model. It is found that the damping of CAPE by fast convective exchange as assumed in the WISHE theory inhibits substantial intensification in the model. This result can be explained by the dominance of the secondary circulation over surface heat transfer in the growth stage. It leads to entrainment of low entropy air into the eyewall resulting in the weakening of the cyclone. Other simulations reveal that the intensification rate increases with increasing initial CAPE and that the inner core CAPE is smaller than that of the ambient region. Investigations with the more complex Ooyama model yield qualitatively similar results. In this model, two types of convection are considered. The first one is based on frictional convergence in the boundary layer and the second one describes a convective adjustment including a precipitation efficiency. Only frictionally induced convection supports tropical cyclone intensification while the second one strongly acts to dampen the cyclone. Finally, the complex nonhydrostatic cloud model CM1 is used where the initial CAPE is varied. This model also exposes the existence of radially increasing CAPE during intensification. The experiments of this study indicate a positive relationship between the radial CAPE gradient and the intensification rate which disagrees with the basic assumption of WISHE models. The results emphasise the role of the secondary circulation for transporting high entropy air into the tropical cyclone inner core, and therefore should be considered in a proper intensification theory as has been done in the rotating convection paradigm by Montgomery and Smith.

Keywords: tropical cyclone intensification, convective available potential energy, wind-induced surface heat exchange, eyewall and secondary circulation

Read: Lee, M., & Frisius, T. (2018). On the role of convective available potential energy (CAPE) in tropical cyclone intensification. Tellus Series A-Dynamic Meteorology and Oceanography, 70(1): 1433433, pp. 1-19. doi:10.1080/16000870.2018.1433433.

Online: https://doi.org/10.1080/16000870.2018.1433433

Date issued: March 2018

Improved teleconnection-based dynamical seasonal predictions of boreal winter

Abstract: Climate and weather variability in the North Atlantic region is determined largely by the North Atlantic Oscillation (NAO). The potential for skillful seasonal forecasts of the winter NAO using an ensemble‐based dynamical prediction system has only recently been demonstrated. Here we show that the winter predictability can be significantly improved by refining a dynamical ensemble through subsampling. We enhance prediction skill of surface temperature, precipitation, and sea level pressure over essential parts of the Northern Hemisphere by retaining only the ensemble members whose NAO state is close to a “first guess” NAO prediction based on a statistical analysis of the initial autumn state of the ocean, sea ice, land, and stratosphere. The correlation coefficient between the reforecasted and observation‐based winter NAO is significantly increased from 0.49 to 0.83 over a reforecast period from 1982 to 2016, and from 0.42 to 0.86 for a forecast period from 2001 to 2017. Our novel approach represents a successful and robust alternative to further increasing the ensemble size, and potentially can be used in operational seasonal prediction systems.

Read: Dobrynin, M., Domeisen, D., Müller, W. A., Bell, L., Brune, S., Bunzel, F., Fröhlich, C., Pohlmann, H., & Baehr, J. (2018). Improved teleconnection-based dynamical seasonal predictions of boreal winter. Geophysical Research Letters, early view, available online. doi:10.1002/2018GL077209.

Online: https://doi.org/10.1002/2018GL077209

Contact: Mikhail Dobrynin (mikhail.dobrynindummy@uni-hamburgdummy2.de)

Date issued: February 2018

Towards an along-track validation of HOAPS precipitation using OceanRAIN optical disdrometer data over the Atlantic Ocean

Abstract: The Hamburg Ocean Atmosphere Parameters and fluxes from Satellite data (HOAPS) passive‐microwave precipitation scan product is compared to the Ocean Rainfall And Ice‐phase precipitation measurement Network (OceanRAIN) surface‐based precipitation reference dataset over the global ocean. For the first time, we apply statistical point‐to‐area adjustments and along‐track averaging to ship‐based OceanRAIN precipitation data over the Atlantic Ocean to better represent collocated precipitation rates within a HOAPS satellite pixel. The statistical adjustments strongly reduce the HOAPS–OceanRAIN root‐mean‐square error from 2.65 mm h−1 to 1.01 mm h−1. Overall, the point‐to‐area effect stronger impacts HOAPS–OceanRAIN differences than the precipitation regime. Higher‐resolved satellite data indicates that these adjustments work best for most convective‐like precipitation cases while some rather stratiform‐like precipitation cases would need no adjustment. Excluding precipitation rates below the HOAPS sensitivity threshold of 0.3 mm h−1 reduces the difference in average precipitation rates between HOAPS hits and false detections combined and OceanRAIN hits and misses combined to 2 %. This precipitation‐rate difference lies below the uncertainty obtained from resampling of about 10 %. Without false detections, the HOAPS precipitation rate of hits‐only exceeds that of OceanRAIN by 50 %. Most of the HOAPS false detections follow from cases when precipitation occurs within the HOAPS pixel but off the ship track. Consequently, these apparent false detections lead to an overestimation of HOAPS precipitation rates compared to OceanRAIN, particularly in the inner tropics and partly mid‐latitudes where clustered convective precipitation occurs most frequently. Misses cause underestimated HOAPS precipitation rates mainly in the mid‐ and high‐latitudes. However, for a HOAPS validation, apparent false detections need to be considered in addition to hits of OceanRAIN precipitation rates to which we successfully applied statistical point‐to‐area adjustments.

Read: Burdanowitz, J., Klepp, C., Bakan, S., & Bühler, S. (in press). Towards an along-track validation of HOAPS precipitation using OceanRAIN optical disdrometer data over the Atlantic Ocean. Quarterly Journal of the Royal Meteorological Society, accepted manuscript, available online. doi:10.1002/qj.3248.

Online: https://doi.org/10.1002/qj.3248

Contact: Jörg Burdanowitz (joerg.burdanowitzdummy@uni-hamburgdummy2.de)

Date issued: February 2018

On the role of horizontal resolution over the Tibetan Plateau in the REMO regional climate model

Abstract: A number of studies have shown that added value is obtained by increasing the horizontal resolution of a regional climate model to capture additional fine-scale weather processes. However, the mechanisms leading to this added value are different over areas with complicated orographic features, such as the Tibetan Plateau (TP). To determine the role that horizontal resolution plays over the TP, a detailed comparison was made between the results from the REMO regional climate model at resolutions of 25 and 50 km for the period 1980–2007. The model was driven at the lateral boundaries by the European Centre for Medium-Range Weather Forecasts Interim Reanalysis data. The experiments differ only in representation of topography, all other land parameters (e.g., vegetation characteristics, soil texture) are the same. The results show that the high-resolution topography affects the regional air circulation near the ground surface around the edge of the TP, which leads to a redistribution of the transport of atmospheric water vapor, especially over the Brahmaputra and Irrawaddy valleys—the main water vapor paths for the southern TP—increasing the amount of atmospheric water vapor transported onto the TP by about 5%. This, in turn, significantly decreases the temperature at 2 m by > 1.5 °C in winter in the high-resolution simulation of the southern TP. The impact of topography on the 2 m temperature over the TP is therefore by influencing the transport of atmospheric water vapor in the main water vapor paths.

Keywords: REMO regional climate model, Validation, High-resolution, Added value, Tibetan Plateau 

Read: Xu, J., Koldunov, N., Remedio, A.R.C. et al. Clim Dyn (2018). On the role of horizontal resolution over the Tibetan Plateau in the REMO regional climate model. Climate Dynamics, doi: 10.1007/s00382-018-4085-7Zhu.

Online: https://doi.org/10.1007/s00382-018-4085-7

Date issued: December 2017

Visualization in Meteorology – A Survey of Techniques and Tools for Data Analysis Tasks, IEEE Transactions on Visualization and Computer Graphics

Abstract: This article surveys the history and current state of the art of visualization in meteorology, focusing on visualization techniques and tools used for meteorological data analysis. We examine characteristics of meteorological data and analysis tasks, describe the development of computer graphics methods for visualization in meteorology from the 1960s to today, and visit the state of the art of visualization techniques and tools in operational weather forecasting and atmospheric research. We approach the topic from both the visualization and the meteorological side, showing visualization techniques commonly used in meteorological practice, and surveying recent studies in visualization research aimed at meteorological applications. Our overview covers visualization techniques from the fields of display design, 3D visualization, flow dynamics, feature-based visualization, comparative visualization and data fusion, uncertainty and ensemble visualization, interactive visual analysis, efficient rendering, and scalability and reproducibility. We discuss demands and challenges for visualization research targeting meteorological data analysis, highlighting aspects in demonstration of benefit, interactive visual analysis, seamless visualization, ensemble visualization, 3D visualization, and technical issues.

Keywords: Visualization, meteorology, atmospheric science, weather forecasting, climatology, spatiotemporal data, survey

Read: Rautenhaus, M., Böttinger, M., Siemen, S., Hoffman, R., Kirby, R. M., Mirzargar, M., Röber, N., and Westermann, R. (2017). Visualization in Meteorology – A Survey of Techniques and Tools for Data Analysis Tasks, IEEE Transactions on Visualization and Computer Graphics, doi:10.1109/TVCG.2017.2779501

Date issued: March 2018

Assessment of Flood Losses with Household Responses: Agent-Based Simulation in an Urban Catchment Area

Densely populated coastal urban areas are often exposed to multiple hazards, in particular floods and storms. Flood defenses and other engineering measures contribute to the mitigation of flood hazards, but a holistic approach to flood risk management should consider other interventions from the human side, including warning information, adaptive behavior, people/property evacuation, and the multilateral relief in local communities. There are few simulation approaches to consider these factors, and these typically focus on collective human actions. This paper presents an agent-based model that simulates flood response preferences and actions taken within individual households to reduce flood losses. The model implements a human response framework in which agents assess different flood scenarios according to warning information and decide whether and how much they invest in response measures to reduce potential inundation damages. A case study has been carried out in the Ng Tung River basin, an urbanized watershed in northern Hong Kong. Adopting a digital elevation model (DEM) as the modeling environment and a building map of household locations in the case area, the model considers the characteristics of households and the flood response behavior of their occupants. We found that property value, warning information, and storm conditions all influence household losses, with downstream and high density areas being particularly vulnerable. Results further indicate (i) that a flood warning system, which provides timely, accurate, and broad coverage rainstorm warning, can reduce flood losses by 30–40%; and (ii) to reduce losses, it is more effective and cheaper to invest early in response measures than late actions. This dynamic agent-based modeling approach is an innovative attempt to quantify and model the role of human responses in flood loss assessments. The model is demonstrated being useful for analyzing household scale flood losses and responses and it has the potential to contribute to flood emergency planning resource allocation in pluvial flood incidents.

Keywords: Flood risk and damage, Flood loss assessment, Adaptation and response, Urban area, Agent-based modeling, Pearl River Delta, Hong Kong

Read: Yang, L., Scheffran, J., Süsser, D., Dawson, R., & Chen, Y. (2018). Assessment of Flood Losses with Household Responses: Agent-Based Simulation in an Urban Catchment Area. Environmental Modeling & Assessment, 1-20. doi:10.1007/s10666-018-9597-3.

Online: https://doi.org/10.1007/s10666-018-9597-3

Contact: Jürgen Scheffran (juergen.scheffradummy@uni-hamburgdummy2.de)

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Date issued: March 2018

Investigating the role of meltwater versus precipitation seasonality in abrupt lake-level rise in the high-altitude Tso Moriri Lake (India)

Abstract: We present late Quaternary lake level reconstruction from the high altitude Tso Moriri Lake (NW Indian Himalaya) using a combination of new and published data from shallow and deep water cores, and catchment geomorphology. Our reconstruction indicates two dramatic lake level increases – a late glacial (ca. 16.4–12.6 cal kyr B.P.) rise of 65 m, and a 47 m rise during the early Holocene wet phase (ca. 11.2–8.5 cal kyr B.P.) which are separated by the Younger Dryas (YD) event. We decouple the role of precipitation seasonality and snow melt using a combination of proxies sensitive to the Indian Summer Monsoon (ISM), and a regional spatio-temporal transect that provides information on the eastward penetration of the winter westerlies. A comparison of shallow and deep water cores shows that (i) the first lake level increase (~ 65 m, ca. 16.4–12.6 cal kyr B.P.) is caused by melt water inflow triggered by the increasing summer insolation; (ii) the second lake level increase (~ 47 m, 11.2–8.5 cal kyr B.P.) is largely caused by a rise in annual precipitation coupled with reduced summer evaporation; (iii) in contrast to the onset of ISM (Bay of Bengal branch) at ca. 14.7 ka in lower elevations in NE India, the hydroclimatic influence of ISM in the high altitude Himalaya is seen only between 12.7 and 12 cal kyr B.P., though the influence of solar insolation (via increased snowmelt) is visible from 16.4 cal kyr B.P. onwards; (iv) the eastward penetration of westerlies in Indian Himalayas is strongly influenced by the strength of the Siberian High.

Keywords: Indian Summer Monsoon, Westerlies, Lake level reconstruction, Endogenic carbonates

Read: Mishra, P., Prasad, S., Jehangir, A., Ammbili, A., Yousuf, A.R., Gaye, B. (2018). Investigating the role of meltwater versus precipitation seasonality in abrupt lake-level rise in the high-altitude Tso Moriri Lake (India). Palaeogeography, Palaeoclimatology, Palaeoecology, 493, 20-29. doi. 10.1016/j.palaeo.2017.12.026

Online: https://doi.org/10.1016/j.palaeo.2017.12.026

Contact: Birgit Gaye (birgit.gayedummy@uni-hamburgdummy2.de)

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Date issued: February 2018

The role of life cycle processes on phytoplankton spring bloom composition: a modelling study applied to the Gulf of Finland

Diatoms are typical representatives of the spring bloom worldwide. In several parts of the Baltic Sea, however, cold-water dinoflagellates such as Biecheleria baltica have become dominant during the past decades. We have investigated the mechanisms behind this trend by using an ecosystem model which includes the life cycles of three main phytoplankton groups (diatoms, dinoflagellates and cyanobacteria). Coupled to a water column model we have applied the model system for the period 1981–2010 to the Gulf of Finland. In agreement with observations, the model results show an increasing trend in the proportion of dinoflagellates in the Gulf of Finland. Temperature and life cycle-related processes explain the relative increase of dinoflagellates and corresponding decrease of diatoms. Warming over the 30 years has enabled a head start of dinoflagellates by reducing the time lag between germination and growth of vegetative cells. Although diatoms have a much higher growth rate, they cannot compete with the high dinoflagellate concentrations that result from the inoculum. Diatoms will only dominate in years when the inoculum concentrations of dinoflagellates or the temperatures are low. Overall, the model results suggest that consideration of life cycle dynamics of competing phytoplankton groups may be crucial to understand trends and shifts in community composition.

Keywords: Baltic Sea, Life cycle, Cold-water dinoflagellates, Diatoms, Resting stages, Seed pool, Spring bloom

Read: Lee, S., Hofmeister, R., & Hense, I. (2018). The role of life cycle processes on phytoplankton spring bloom composition: a modelling study applied to the Gulf of Finland. Journal of Marine Systems, 178, 75-85. doi:10.1016/j.jmarsys.2017.10.010.

Online: https://doi.org/10.1016/j.jmarsys.2017.10.010

Contact: Inga Hense (inga.hensedummy@uni-hamburgdummy2.de)

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Date issued: February 2018

Mapping the Spatiotemporal Dynamics of Europe's Land Surface Temperatures

The land surface temperature (LST) drives many terrestrial biophysical processes and varies rapidly in space and time primarily due to the earth's diurnal and annual cycles. Models of the diurnal and annual LST cycle retrieved from satellite data can be reduced to several gap-free parameters that represent the surface's thermal characteristics and provide a generalized characterization of the LST temporal dynamics. In this letter, we use such an approach to map Europe's annual and diurnal LST dynamics. In particular, we reduce a five-year time series (2009-2013) of diurnal LST from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) to 48 sets of half-hourly annual cycle parameters (ACPs), namely, the mean annual LST, the yearly amplitude of LST, and the LST phase shift from the spring equinox. The derived data provide a complete representation of how mainland Europe responds to the heating of the sun and the nighttime LST decay and reveal how Europe's biogeographic regions differ in that respect. We further argue that the SEVIRI ACP can provide an observation-based spatially consistent background for studying and characterizing the thermal behavior of the surface and also a data set to support climate classification at a finer spatial resolution.

Keywords: Land surface temperature, Europe, Land surface, Earth, Satellites, Meteorology, Temperature sensors

Read: Bechtel, B., Sismanidis, P., Keramitsoglou, I., & Kiranoudis, C. T. (2018). Mapping the Spatiotemporal Dynamics of Europe's Land Surface Temperatures. IEEE Geoscience and Remote Sensing Letters, 15(2), 202-206. doi: 10.1109/LGRS.2017.2779829.

Online: https://doi.org/10.1109/LGRS.2017.2779829

Contact: Benjamin Bechtel (benjamin.bechteldummy@uni-hamburgdummy2.de)

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Date issued: February 2018

A Pilot Climate Sensitivity Study using the CEN Coupled Adjoint Model

A pilot coupled climate sensitivity study is presented based on the newly developed adjoint coupled climate model, Centrum für Erdsystemforschung und Nachhaltigkeit (CEN) Earth System Assimilation Model (CESAM). To this end the components of the coupled forward model are summarized, and the generation of the adjoint code out of the model forward code through the application of the Transformation of Algorithms in FORTRAN (TAF) adjoint compiler is discussed. It is shown that simulations of the intermediate-complexity CESAM are comparable in quality to CMIP-type coupled climate models, justifying the usage of the model to compute adjoint sensitivities of the northern Europe near-surface temperature to anomalies in surface temperature, sea surface salinity, and sea ice over the North Atlantic and the Arctic on time scales of up to one month. Results confirm that on a time scale of up to a few days surface temperatures over northern Europe are influenced by Atlantic temperature anomalies just upstream of the target location. With increasingly longer time lapse, however, it is the influence of SSTs over the central and western North Atlantic on the overlying atmosphere and the associated changes in storm-track pattern that dominate the evolution of the surface European temperature. Influences of surface salinity and sea ice on the northern European temperature appear to have similar sensitivity mechanisms, invoked indirectly through their influence on near-surface temperature anomalies. The adjoint study thus confirms that the SST’s impact on the atmospheric dynamics, notably storm tracks, is the primary cause for the influence of northern European temperature changes.

Keywords: Climate models; Data assimilation; Numerical analysis/modeling

Read: Stammer, D., Köhl, A., Vlasenko, A., Matei, I., Lunkeit, F., & Schubert, S. (2018). A Pilot Climate Sensitivity Study using the CEN Coupled Adjoint Model. Journal of Climate, 2031-2056. doi:10.1175/JCLI-D-17-0183.1.

Online: https://doi.org/10.1175/JCLI-D-17-0183.1

Contact: Detlef Stammer (detlef.stammerdummy@uni-hamburgdummy2.de)

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Date issued: February 2018

Awareness of sea-level response under climate change on the coast of Ghana

In response to climate change, coastal communities are expected to experience increasing coastal impacts of sea-level rise (SLR). Strategies formulated and implemented to curb these impacts can thus be more effective if scientific findings on the response to climate change and SLR impacts on coastal communities are taken into consideration and not based merely on the need for coastal protection due to physical coastal erosion. There is also the need to determine the level of awareness of sea-level rise and responses in coastal communities to improve adaptation planning. This study assesses the impact of future erosion on the coastal land cover of Ghana. This assessment estimates approximately 2.66 km2, 2.77 km2, and 3.24 km2 of coastal settlements, 2.10 km2, 2.20 km2 and 2.58 km2 of lagoons, 1.39 km2, 1.46 km2 and 1.71 km2 of wetlands to be at risk of inundation by the year 2050 based on coastal erosion estimates for the 2.6, 4.5 and 8.5 Representative Concentration Pathways (RCPs) used in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). This study also assesses the level of awareness of respondents to SLR on the coast of Ghana and explores the availability and level of integration of scientific knowledge of SLR into coastal adaptation strategies in Ghana. Assessment of the awareness of SLR responses to the changing climate in Ghana is made through semi-structured interviews at national, municipal/district and coastal community scales. Although settlements may be inundated based on the coastal erosion estimates, coastal dwellers interviewed cherish their proximity to the sea and are determined to maintain their occupancy close to the sea as spatial location influences their source of livelihood (fishing). Respondents lack knowledge/understanding of SLR, as the majority of household interviewees attributed the rise or fall in sea level to God. Respondents from Ngiresia alleged that the ongoing coastal sea defence project in their community has led to increased malaria cases.

Keywords: Climate change, Climate change adaptation, Coastal impacts, Geographic information systems, Sea-level rise

Read: Evadzi, P. I. K., Scheffran, J., Zorita, E., & Hünicke, B. (2018). Awareness of sea-level response under climate change on the coast of Ghana. Journal of Coastal Conservation, 22(1), 183-197. doi:10.1007/s11852-017-0569-6.

Online: https://doi.org/10.1007/s11852-017-0569-6

Contact: Jürgen Scheffran (juergen.scheffradummy@uni-hamburgdummy2.de)

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Date issued: February 2018

Coast to coast: current multidisciplinary research trends in German coastal and marine geography

Read: Link, M., Borchert, L., Süsser, D., & von Prondzinski, P. (2018). Coast to coast: current multidisciplinary research trends in German coastal and marine geography. Journal of Coastal Conservation, 22(Spec. Iss.), 1-4. doi:10.1007/s11852-017-0578-5.

Online: https://doi.org/10.1007/s11852-017-0578-5

Contact: Michael Link (michael.linkdummy@uni-hamburgdummy2.de)

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Date issued: February 2018

Contrasting pattern of hydrological changes during the past two millennia from central and northern India: Regional climate difference or anthropogenic impact?

Abstract: High resolution reconstructions of the India Summer Monsoon (ISM) are essential to identify regionally different patterns of climate change and refine predictive models. We find opposing trends of hydrological proxies between northern (Sahiya cave stalagmite) and central India (Lonar Lake) between 100 and 1300 CE with the strongest anti-correlation between 810 and 1300 CE. The apparently contradictory data raise the question if these are related to widely different regional precipitation patterns or reflect human influence in/around the Lonar Lake. By comparing multiproxy data with historical records, we demonstrate that only the organic proxies in the Lonar Lake show evidence of anthropogenic impact. However, evaporite data (mineralogy and δ18O) are indicative of precipitation/evaporation (P/E) into the Lonar Lake. Back-trajectories of air-mass circulation over northern and central India show that the relative contribution of the Bay of Bengal (BoB) branch of the ISM is crucial for determining the δ18O of carbonate proxies only in north India, whereas central India is affected significantly by the Arabian Sea (AS) branch of the ISM. We conclude that the δ18O of evaporative carbonates in the Lonar Lake reflects P/E and, in the interval under consideration, is not influenced by source water changes. The opposing trend between central and northern India can be explained by (i) persistent multidecadal droughts over central India between 810 and 1300 CE that provided an effective mechanism for strengthening sub-tropical westerly winds resulting in enhancement of wintertime (non-monsoonal) rainfall over northern parts of the Indian subcontinent, and/or (ii) increased moisture influx to northern India from the depleted BoB source waters.

Keywords: ENSO, Isotopes, Indian summer monsoon, Lonar Lake, Stalagmites, Westerlies

Read: Mishra, P. K., Prasad, S., Marwan, N., Anoop, A., Krishnan, R., Gaye, B., Basavaiah, N., Stebich, M., Menzel, P., and Riedel, N. (2018). Contrasting pattern of hydrological changes during the past two millennia from central and northern India: Regional climate difference or anthropogenic impact?, Global and Planetary Change, 161, 97-107. doi.10.1016/j.gloplacha.2017.12.005

Online: https://doi.org/10.1016/j.gloplacha.2017.12.005

Contact: Birgit Gaye (birgit.gayedummy@uni-hamburgdummy2.de)

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Date issued: January 2018

The KLIWAS North Sea climatology. Part I: Processing of the atmospheric data

Climatological reference data serve as validation of regional climate models, as the boundary condition for the model runs, and as input for assimilation systems used by reanalyses. Within the framework of the interdisciplinary research program Climate Water Navigation (KLIWAS): Impacts of Climate Change on Waterways and Navigation of the German Federal Ministry of Transport and Digital Infrastructure, a new climatology of the North Sea and adjacent regions was developed in an joint effort by the Federal Maritime and Hydrographic Agency, the German Weather Service [Deutscher Wetterdienst (DWD)], and the Integrated Climate Data Center (ICDC) of the University of Hamburg. Long-term records of monthly and annual mean 2-m air temperature, dewpoint temperature, and sea level pressure data from 1950 to 2010 were calculated on a horizontal 1° × 1° grid. All products were based on quality-controlled data from DWD’s Marine Data Centre. Correction methods were implemented for each parameter to reduce the sampling error resulting from the sparse coverage of observations in certain regions. Comparisons between sampling error estimates based on ERA-40 and the climatology products show that the sampling error was reduced effectively. The climatologies are available for download on the ICDC’s website and will be updated regularly regarding new observations and additional parameters. An extension to the Baltic Sea is in progress.

Keywords: In situ atmospheric observations

Read: Sadikni, R., Schade, N. H., Jahnke-Bornemann, A., Hinrichs, I., Stammer, D., Dümenil-Gates, L., Tinz, B., & Andersson, A. (2018). The KLIWAS North Sea climatology. Part I: Processing of the atmospheric data. Journal of Atmospheric and Oceanic Technology, 35(1), 111-126. doi:10.1175/JTECH-D-17-0044.1.

Online: https://doi.org/10.1175/JTECH-D-17-0044.1

Contact: Remon Sadiki (remon.sadikidummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Sedimentary dynamics and high-frequency sequence stratigraphy of the southwestern slope of Great Bahama Bank

New geophysical data from the leeward slope of Great Bahama Bank show how contour currents shape the slope and induce re-sedimentation processes. Along slope segments with high current control, drift migration and current winnowing at the toe of slope form a deep moat. Here, the slope progradation is inhibited by large channel incisions and the accumulation of large mass transport complexes, triggered by current winnowing. In areas where the slope is bathed by weaker currents, the accumulation of mass transport complexes and channel incision is rather controlled by the position of the sea level. Large slope failures were triggered during the Mid-Pleistocene transition and Mid-Brunhes event, both periods characterized by changes in the cyclicity or the amplitude of sea-level fluctuations. Within the seismic stratigraphic framework of third order sequences, four sequences of higher order were identified in the succession of the upper Pleistocene. These higher order sequences also show clear differences in function of the slope exposure to contour currents. Two stochastic models emphasize the role of the contour currents and slope morphology in the facies distribution in the upper Pleistocene sequences. In areas of high current influence the interplay of erosional and depositional processes form a complex facies pattern with downslope and along strike facies alterations. In zones with lower current influence, major facies alternations occur predominately in downslope direction, and a layer-cake pattern characterizes the along strike direction. Therefore, this study highlights that contour currents are an underestimated driver for the sediment distribution and architecture of carbonate slopes.

Keywords: Bahamas, Carbonate slopes, Contour currents, Slope morphology, Seismic stratigraphy, Facies modeling

Read: Wunsch, M., Betzler, C., Eberli, G. P., Lindhorst, S., Ludmann, T., & Reijmer, J. J. G. (2018). Sedimentary dynamics and high-frequency sequence stratigraphy of the southwestern slope of Great Bahama Bank. Sedimentary Geology, 363, 96-117. doi:10.1016/j.sedgeo.2017.10.013.

Online: https://doi.org/10.1016/j.sedgeo.2017.10.013

Contact: Marco Wunsch (marco.wunschdummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Glacial-Interglacial changes and Holocene variations in Arabian Sea denitrification

Abstarct: At present, the Arabian Sea has a permanent oxygen minimum zone (OMZ) at water depths between about 100 and 1200 m. Active denitrification in the upper part of the OMZ is recorded by enhanced δ15N values in the sediments. Sediment cores show a δ15N increase during the middle and late Holocene, which is contrary to the trend in the other two regions of water column denitrification in the eastern tropical North and South Pacific. We calculated composite sea surface temperature (SST) and δ15N ratios in time slices of 1000 years of the last 25 kyr to better understand the reasons for the establishment of the Arabian Sea OMZ and its response to changes in the Asian monsoon system. Low δ15N values of 4–7 ‰ during the last glacial maximum (LGM) and stadials (Younger Dryas and Heinrich events) suggest that denitrification was inactive or weak during Pleistocene cold phases, while warm interstadials (ISs) had elevated δ15N. Fast changes in upwelling intensities and OMZ ventilation from the Antarctic were responsible for these strong millennial-scale variations during the glacial. During the entire Holocene δ15N values  >  6 ‰ indicate a relatively stable OMZ with enhanced denitrification. The OMZ develops parallel to the strengthening of the SW monsoon and monsoonal upwelling after the LGM. Despite the relatively stable climatic conditions of the Holocene, the δ15N records show regionally different trends in the Arabian Sea. In the upwelling areas in the western part of the basin, δ15N values are lower during the mid-Holocene (4.2–8.2 ka BP) compared to the late Holocene ( <  4.2 ka BP) due to stronger ventilation of the OMZ during the period of the most intense southwest monsoonal upwelling. In contrast, δ15N values in the northern and eastern Arabian Sea rose during the last 8 kyr. The displacement of the core of the OMZ from the region of maximum productivity in the western Arabian Sea to its present position in the northeast was established during the middle and late Holocene. This was probably caused by (i) reduced ventilation due to a longer residence time of OMZ waters and (ii) augmented by rising oxygen consumption due to enhanced northeast-monsoon-driven biological productivity. This concurs with the results of the Kiel Climate Model, which show an increase in OMZ volume during the last 9 kyr related to the increasing age of the OMZ water mass.

Read: Gaye, B., Böll, A., Segschneider, J., Burdanowitz, N., Emeis, K. C., Ramaswamy, V., Lahajnar, N., Lückge, A., and Rixen, T. (2018). Glacial-Interglacial changes and Holocene variations in Arabian Sea denitrification, Biogeosciences, 15, 507-527. doi.10.5194/bg-15-507-2018

Online: https://doi.org/10.5194/bg-15-507-2018

Contact: Birgit Gaye (birgit.gayedummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Inferring Missing Climate Data for Agricultural Planning Using Bayesian Networks

Climate data availability plays a key role in development processes of policies, services, and planning in the agricultural sector. However, data at the spatial or temporal resolution required is often lacking, or certain values are missing. In this work, we propose to use a Bayesian network approach to generate data for missing variables. As a case study, we use relative humidity, which is an important indicator of land suitability for coffee production. For the model, we first extracted climate data for the variables precipitation, maximum and minimum air temperature, wind speed, solar radiation and relative humidity from the surface reanalysis dataset Climate Forecast System Reanalysis. We then used machine learning algorithms to define the model structure and parameters from the relationships of the variables found in the dataset. Precipitation, maximum and minimum air temperature, wind speed, and solar radiation are then used as proxy variables to infer missing values for monthly relative humidity and relative humidity for the driest month. For this, we used both complete and incomplete initial data. In both scenarios of data availability, the comparison of estimated and measured values of relative humidity shows a high level of agreement. We conclude that using Bayesian Networks is a practical solution to estimate relative humidity for coffee agricultural planning.

Read: Lara-Estrada, L. D., Rasche, L., Sucar, L. E., & Schneider, U. (2018). Inferring Missing Climate Data for Agricultural Planning Using Bayesian Networks. Land, 7 (1): 4, pp. 1-13. doi:10.3390/land7010004.

Online: https://doi.org/10.3390/land7010004

Contact: Leonel Lara Estrada (leonel.lara.estradadummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Predictability and Non-Gaussian Characteristics of the North Atlantic Oscillation

The North Atlantic Oscillation (NAO) is the dominant mode of climate variability over the North Atlantic basin and has a significant impact on seasonal climate and surface weather conditions. It is the result of complex and nonlinear interactions between many spatiotemporal scales. Here, the authors study the statistical properties of two time series of the daily NAO index. Previous NAO modeling attempts only considered Gaussian noise, which can be inconsistent with the system complexity. Here, it is found that an autoregressive model with non-Gaussian noise provides a better fit to the time series. This result holds also when considering time series for the four seasons separately. The usefulness of the proposed model is evaluated by means of an investigation of its forecast skill.

Keywords: Teleconnections; Time series; Probability forecasts/models/distribution; Stochastic models; North Atlantic Oscillation

Read: Önskog, T., Franzke, C., & Hannachi, A. (2018). Predictability and Non-Gaussian Characteristics of the North Atlantic Oscillation. Journal of Climate, 31, 537-554. doi:10.1175/JCLI-D-17-0101.1.

Online: https://doi.org/10.1175/JCLI-D-17-0101.1

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Contribution of atmospheric circulation to recent off-shore sea-level variations in the Baltic Sea and the North Sea

The main purpose of this study is to quantify the contribution of atmospheric factors to recent off-shore sea-level variability in the Baltic Sea and the North Sea on interannual timescales. For this purpose, we statistically analysed sea-level records from tide gauges and satellite altimetry and several climatic data sets covering the last century.

Previous studies had concluded that the North Atlantic Oscillation (NAO) is the main pattern of atmospheric variability affecting sea level in the Baltic Sea and the North Sea in wintertime. However, we identify a different atmospheric circulation pattern that is more closely connected to sea-level variability than the NAO. This circulation pattern displays a link to sea level that remains stable through the 20th century, in contrast to the much more variable link between sea level and the NAO. We denote this atmospheric variability mode as the Baltic Sea and North Sea Oscillation (BANOS) index. The sea-level pressure (SLP) BANOS pattern displays an SLP dipole with centres of action located over (5° W, 45° N) and (20° E, 70° N) and this is distinct from the standard NAO SLP pattern in wintertime. In summertime, the discrepancy between the SLP BANOS and NAO patterns becomes clearer, with centres of action of the former located over (30° E, 45° N) and (20° E, 60° N).

This index has a stronger connection to off-shore sea-level variability in the study area than the NAO in wintertime for the period 1993–2013, explaining locally up to 90 % of the interannual sea-level variance in winter and up to 79 % in summer. The eastern part of the Gulf of Finland is the area where the BANOS index is most sensitive to sea level in wintertime, whereas the Gulf of Riga is the most sensitive region in summertime. In the North Sea region, the maximum sea-level sensitivity to the BANOS pattern is located in the German Bight for both winter and summer seasons.

We investigated, and when possible quantified, the contribution of several physical mechanisms which may explain the link between the sea-level variability and the atmospheric pattern described by the BANOS index. These mechanisms include the inverse barometer effect (IBE), freshwater balance, net energy surface flux and wind-induced water transport. We found that the most important mechanism is the IBE in both wintertime and summertime. Assuming a complete equilibration of seasonal sea level to the SLP gradients over this region, the IBE can explain up to 88 % of the sea-level variability attributed to the BANOS index in wintertime and 34 % in summertime. The net energy flux at the surface is found to be an important factor for the variation of sea level, explaining 35 % of sea-level variance in wintertime and a very small amount in summer. The freshwater flux could only explain 27 % of the variability in summertime and a negligible part in winter. In contrast to the NAO, the direct wind forcing associated with the SLP BANOS pattern does not lead to transport of water from the North Sea into the Baltic Sea in wintertime.

Read: Karabil, S., Zorita, E., & Hünicke, B. (2018). Contribution of atmospheric circulation to recent off-shore sea-level variations in the Baltic Sea and the North Sea. Earth System Dynamics, 9, 69-90. doi:10.5194/esd-9-69-2018.

Online: http://doi.org/10.5194/esd-9-69-2018

Contact: Sitar Karabil (sitar.karabildummy@hzgdummy2.de)

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Date issued: January 2018

How Predictable Are the Arctic and North Atlantic Oscillations? Exploring the Variability and Predictability of the Northern Hemisphere

The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) describe the dominant part of the variability in the Northern Hemisphere extratropical troposphere. Because of the strong connection of these patterns with surface climate, recent years have shown an increased interest and an increasing skill in forecasting them. However, it is unclear what the intrinsic limits of short-term predictability for the NAO and AO patterns are. This study compares the variability and predictability of both patterns, using a range of data and index computation methods for the daily NAO and AO indices. Small deviations from Gaussianity are found along with characteristic decorrelation time scales of around one week. In the analysis of the Lyapunov spectrum it is found that predictability is not significantly different between the AO and NAO or between reanalysis products. Differences exist, however, between the indices based on EOF analysis, which exhibit predictability time scales around 12–16 days, and the station-based indices, exhibiting a longer predictability of 18–20 days. Both of these time scales indicate predictability beyond that currently obtained in ensemble prediction models for short-term predictability. Additional longer-term predictability for these patterns may be gained through local feedbacks and remote forcing mechanisms for particular atmospheric conditions.

Keywords: Arctic Oscillation; North Atlantic Oscillation; Forecasting; Climate variability

Read: Badin, G., Domeisen, D. I. V., & Koszalka, I. M. (2018). How Predictable Are the Arctic and North Atlantic Oscillations? Exploring the Variability and Predictability of the Northern Hemisphere. Journal of Climate, 31(3), 997-1014. doi:10.1175/JCLI-D-17-0226.1.

Online: https://doi.org/10.1175/JCLI-D-17-0226.1

Contact: Gualtiero Badin (gualtiero.badindummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Strengthening seasonal marine CO2 variations due to increasing atmospheric CO2

The increase of atmospheric CO2 has been predicted to impact the seasonal cycle of inorganic carbon in the global ocean, yet the observational evidence to verify this prediction has been missing. Here, using an observation-based product of the oceanic partial pressure of CO2 (pCO2) covering the past 34 years, we find that the winter-to-summer difference of the pCO2 has increased on average by 2.2 ± 0.4 μatm per decade from 1982 to 2015 poleward of 10° latitude. This is largely in agreement with the trend expected from thermodynamic considerations. Most of the increase stems from the seasonality of the drivers acting on an increasing oceanic pCO2 caused by the uptake of anthropogenic CO2 from the atmosphere. In the high latitudes, the concurrent ocean-acidification-induced changes in the buffer capacity of the ocean enhance this effect. This strengthening of the seasonal winter-to-summer difference pushes the global ocean towards critical thresholds earlier, inducing stress to ocean ecosystems and fisheries. Our study provides observational evidence for this strengthening seasonal difference in the oceanic carbon cycle on a global scale, illustrating the inevitable consequences of anthropogenic CO2 emissions.

Keywords: Biogeochemistry, Climate-change impacts, Marine chemistry

Read: Landschützer, P., Gruber, N., Bakker, D. C. E., Stemmler, I., & Six, K. D. (2018). Strengthening seasonal marine CO2 variations due to increasing atmospheric CO2. Nature Climate Change. doi:10.1038/s41558-017-0057-x.

Online: http://doi.org/10.1038/s41558-017-0057-x

Contact: Katharina Six (katharina.sixdummy@mpimet.mpgdummy2.de)

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Date issued: January 2018

Adjoint-based climate model tuning: application to the Planet Simulator

The adjoint method is used to calibrate the medium complexity climate model “Planet Simulator” through parameter estimation. Identical twin experiments demonstrate that this method can retrieve default values of the control parameters when using a long assimilation window of the order of 2 months. Chaos synchronization through nudging, required to overcome limits in the temporal assimilation window in the adjoint method, is employed successfully to reach this assimilation window length. When assimilating ERA-Interim reanalysis data, the observations of air temperature and the radiative fluxes are the most important data for adjusting the control parameters. The global mean net longwave fluxes at the surface and at the top of the atmosphere are significantly improved by tuning two model parameters controlling the absorption of clouds and water vapor. The global mean net shortwave radiation at the surface is improved by optimizing three model parameters controlling cloud optical properties. The optimized parameters improve the free model (without nudging terms) simulation in a way similar to that in the assimilation experiments. Results suggest a promising way for tuning uncertain parameters in nonlinear coupled climate models.

Read: Lyu, G., Köhl, A., Matei, I., & Stammer, D. (2018). Adjoint-based climate model tuning: application to the Planet Simulator. Journal of Advances in Modeling Earth Systems, 10, early view, available online. doi:10.1002/2017MS001194.

Online: https://doi.org/10.1002/2017MS001194

Contact: Guokun Lyu (guokun.lyudummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Benefits of coordinated water resource system planning in the Cauca-Magdalena River Basin

The Magdalena watershed in Colombia is the most densely populated and economically important region in the country. While Colombia is generally classified as a water-rich country, it is expected that water shortages will occur in the future without adequate planning and investments in water management infrastructures. Currently, even though all instruments required for an integrated water resource management are present in Colombia, they are employed independently from each other and thus not very efficient. To estimate the potential benefits of a more coordinated water management planning, especially in consideration of projected changes in water availability and demand in the near future, we developed a constrained welfare maximization model of the watershed (CAMARI). We ran the model with three different scenarios of future water availability, based on RCPs 2.6, 4.5 and 6.0, and with two planning modes: coordinated and uncoordinated. The results show that a coordinated planning of investments in water management infrastructures increases welfare by 2–18% over the next century in the Magdalena river basin, which corresponds to average annual savings from US$ 610 million to US$ 6.4 billion. Benefits increase as water availability decreases. Our results also show that water demand from the agricultural sector is projected to rise in future, which further underlines the necessity for robust governance mechanisms to keep conflicts between sectors to a minimum.

Keywords: Colombia, capacity expansion, dynamic optimization, investment decisions, water infrastructures

Read: Rasche, L., Schneider, U., Bolivar Lobato, M., Sos del Diego, R., & Stacke, T. (2018). Benefits of coordinated water resource system planning in the Cauca-Magdalena River Basin. Water Economics and Policy, 4: 1650034. doi:10.1142/S2382624X1650034X.

Online: https://doi.org/10.1142/S2382624X1650034X

Contact: Livia Rasche (livia.raschedummy@uni-hamburgdummy2.de)

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Date issued: January 2018

On the Dynamics of Austral Heat Waves

This work examines summer heat wave events in four different regions of Australia (southwest, central, southeast, and northeast) to assess similarities and differences in the circulations that precede, accompany, and follow the heat wave events. A series of circulation composites are constructed for days from 10 days prior to 5 days following onset of each heat wave event. The composites of geopotential height anomalies and wave activity flux vectors show that heat waves in southwest and southeast Australia are preceded by coherent wave train structures in the Indian Ocean region, accompanied by blocking in the Australian region (as an amplified node of the wave train structure), and followed by coherent responses of wave train patterns in the Pacific and South America regions. The heat wave blocking high is maintained by convergence of wave activity in a well-defined wave channel. The concentration of wave activity in the block is aided by the formation of a subtropical jet branch and wave barrier on the equatorward side of the block. Heat waves in central and northeast Australia show similar wave train life cycle responses, but with a proximate ridge in the midtroposphere and a trough in the nearby waveguide region. Heat waves in Australia can be viewed as an element of successive expression of the planetary waveguide modes in the Southern Hemisphere and serve as signifiers of organized, active phases of these modes.

Read: Risbey, J. S., O'Kane, T. J., Monselesan, D. P., Franzke, C., & Horenko, I. (2018). On the Dynamics of Austral Heat Waves. Journal of Geophysical Research-Atmospheres, 123, 38-57. doi:10.1002/2017JD027222.

Online: https://doi.org/10.1002/2017JD027222

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Is It Possible to Distinguish Global and Regional Climate Change from Urban Land Cover Induced Signals? A Mid-Latitude City Example

The local climate in cities differs from the one in rural areas, most prominently characterized by increased surface and air temperatures, known as the “(surface) urban heat island”. As climate has changed and continues to change in all areas of the world, the question arises whether the effects that are noticeable in urban areas are “homemade”, or whether some of them originate from global and regional scale climate changes. Identifying the locally induced changes of urban meteorological parameters is especially relevant for the development of adaptation and mitigation measures. This study aims to distinguish global and regional climate change signals from those induced by urban land cover. Therefore, it provides a compilation of observed and projected climate changes, as well as urban influences on important meteorological parameters. It is concluded that evidence for climate change signals is found predominantly in air temperature. The effect of urban land cover on local climate can be detected for several meteorological parameters, which are air and surface temperature, humidity, and wind. The meteorology of urban areas is a mixture of signals in which the influencing parameters cannot be isolated, but can be assessed qualitatively. Blending interactions between local effects and regional changes are likely to occur.

Read: Wiesner, S., Bechtel, B., Fischereit, J., Grützun, V., Hoffmann, P., Leitl, B., Rechid, D., Schlünzen, H., & Thomsen, S. (2018). Is It Possible to Distinguish Global and Regional Climate Change from Urban Land Cover Induced Signals? A Mid-Latitude City Example. Urban Science, 2(1): 12, pp. 1-22. doi:10.3390/urbansci2010012.

Online: https://doi.org/10.3390/urbansci2010012

Contact: Sarah Wiesner (sarah.wiesnerdummy@uni-hamburgdummy2.de)

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Date issued: January 2018

Improved seasonal prediction of European summer temperatures with new five-layer soil-hydrology scheme

We evaluate the impact of a new five-layer soil-hydrology scheme on seasonal hindcast skill of 2 m temperatures over Europe obtained with the Max Planck Institute Earth System Model (MPI-ESM). Assimilation experiments from 1981 to 2010 and 10-member seasonal hindcasts initialized on 1 May each year are performed with MPI-ESM in two soil configurations, one using a bucket scheme and one a new five-layer soil-hydrology scheme. We find the seasonal hindcast skill for European summer temperatures to improve with the five-layer scheme compared to the bucket scheme and investigate possible causes for these improvements. First, improved indirect soil moisture assimilation allows for enhanced soil moisture-temperature feedbacks in the hindcasts. Additionally, this leads to improved prediction of anomalies in the 500 hPa geopotential height surface, reflecting more realistic atmospheric circulation patterns over Europe.

Read: Bunzel, F., Müller, W. A., Dobrynin, M., Fröhlich, K., Hagemann, S., Pohlmann, H., Stacke, T., & Baehr, J. (2018). Improved seasonal prediction of European summer temperatures with new five-layer soil-hydrology scheme. Geophysical Research Letters, 45, 346-353. doi:10.1002/2017GL076204.

Online: https://doi.org/10.1002/2017GL076204

Contact: Mikhail Dobrynin (Mikhail.dobrynindummy@uni-hamburgdummy2.de)

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Date issued: January 2018

The relationship between Arabian Sea upwelling and Indian Monsoon revisited in a high resolution ocean simulation

Studies based on sediment records, sea-surface temperature and wind suggest that upwelling along the western coast of Arabian Sea is strongly affected by the Indian summer Monsoon. We examine this relationship directly in an eddy-resolving global ocean simulation STORM driven by atmospheric reanalysis over the last 61 years. With its very high spatial resolution (10 km), STORM allows us to identify characteristics of the upwelling system. We analyse the co-variability between upwelling and meteorological and oceanic variables from 1950 to 2010. The analysis reveals high interannual correlations between coastal upwelling and along-shore wind-stress (r = 0.73) as well as with sea-surface temperature (r = −0.83). However, the correlation between the upwelling and the Monsoon is small. We find an atmospheric circulation pattern different from the one that drives the Monsoon as the main modulator of the upwelling variability. In spite of this, the patterns of temperature anomalies that are either linked to Arabian Sea upwelling or to the Monsoon are spatially quite similar, although the physical mechanisms of these links are different. In addition, no long-term trend is detected in our modelled upwelling in the Arabian Sea.

Keywords: Arabian Sea upwelling, Indian summer Monsoon, High resolution ocean simulation

Read: Yi, X., Hünicke, B., Tim, N., & Zorita, E. (2018). The relationship between Arabian Sea upwelling and Indian Monsoon revisited in a high resolution ocean simulation. Climate Dynamics, 50(1-2), 201-213. doi:10.1007/s00382-017-3599-8.

Online: https://doi.org/10.1007/s00382-017-3599-8

Contact: Birgit Hünicke (birgit.huenickedummy@hzgdummy2.de)

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Date issued: January 2018

Impacts of bioenergy policies on land-use change in Nigeria

In recent years, bioenergy policies have increased the competition for land as well as the risk of adverse environmental impacts resulting from deforestation and greenhouse gas emissions (GHGs). Primary land-use objectives confronting society today include meeting the growing demand for agricultural products, especially energy crops, preserving essential ecosystem services for human well-being and long-run agrarian production, and contributing to the climate policy target. Here, future agricultural, societal and environmental consequences of bioenergy policies under different global climate and societal development scenarios were assessed using a novel Forest and Agricultural Sector Optimization Model for Nigeria (NGA–FASOM). The results reveal that, in Nigeria, meeting emission reduction requires an implementation of a minimum carbon price of $80/ton within the forest and agricultural sectors. A carbon price alone is not sufficient to preserve the remaining forests and pasture land in Nigeria when bioenergy is subsidized. Furthermore, the result shows that subsidy on bioenergy does not have any significant effect on the total social welfare. The findings in this study provide a guide for policymakers in designing appropriate policies addressing bioenergy industry issues in Nigeria. View Full-Text

Keywords: bioenergy mandates, bioenergy subsidies, carbon pricing, climate target

Read: Okoro, S., Schickhoff, U., & Schneider, U. (2018). Impacts of bioenergy policies on land-use change in Nigeria. Energies, 11: 152. doi:10.3390/en11010152.

Online: http://doi.org/10.3390/en11010152

Contact: Stanley Okoro (stanley.okorodummy@uni-hamburgdummy2.de)

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Date issued: January 2018

The KLIWAS North Sea Climatology. Part II: Assessment against Global Reanalyses

Observational reference datasets are needed in atmosphere and ocean for quality assessments of climate models and for the evaluation of atmospheric reanalyses. To meet this demand on the regional scale, the Climate Water Navigation (KLIWAS) North Sea climatology (KNSC) was developed. This paper uses KNSC to assess the quality of five atmospheric reanalysis products [ERA-40; ERA-Interim; NCEP-1; 20CR, version 2 (20CRv2); and MERRA] over the North Sea from 1979 to 2001. Differences in sea level pressure (2-m air temperature) can be found in coastal regions for ERA-40/ERA-Interim and MERRA, and are more pronounced during positive (negative) phases of the NAO. 20CRv2 shows biases over the entire North Sea and all seasons of several hectopascals. ERA-40 and ERA-Interim show a negative 2-m air temperature bias relative to KNSC along the coastal mainland of Europe, especially during winter months, possibly a result of a remaining land influence. Mean differences result from winter and fall, mostly remaining within measurement uncertainties. Despite the upgrades in the model setup, ERA-Interim shows negligible differences from ERA-40. 20CRv2 and MERRA show positive (negative) biases during the summer (winter) half year. NCEP-1 follows ERA-40/ERA-Interim but mostly with slightly higher differences. All five reanalyses reproduce the decadal variability and climate shift signals present in KNSC fields. Overall, only 20CRv2 has to be considered as clearly unsatisfactorily regarding biases, MAE, and RMSE compared to all other datasets investigated. This study suggests that similar intercomparison studies, performed over other parts of the world’s oceans, especially coastal regions, can be very helpful in identifying shortcomings in atmospheric reanalysis products.

Keywords: Climatology, Databases, In situ atmospheric observations, Ship observations, Reanalysis data

Read: Sadikni, R., Schade, N. H., Jahnke-Bornemann, A., Hinrichs, I., Stammer, D., Dümenil Gates, L., & Tinz, B. (2018). The KLIWAS North Sea Climatology. Part II: Assessment against Global Reanalyses. Journal of Atmospheric and Oceanic Technology, 35(1), 127-145. doi:10.1175/JTECH-D-17-0045.1.

Online: https://doi.org/10.1175/JTECH-D-17-0045.1

Contact: Remon Sadiki (remon.sadikidummy@uni-hamburgdummy2.de)

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Date issued: December 2017

A proof of concept for scale-adaptive parametrizations: the case of the Lorenz '96 model

Constructing efficient and accurate parametrizations of subgrid-scale processes is a central area of interest in the numerical modelling of geophysical fluids. Using a modified version of the two-level Lorenz ’96 model, we present here a proof of concept of a scale-adaptive parametrization constructed using statistical mechanical arguments. By suitable use of the Ruelle response theory and the Mori–Zwanzig projection method, it is possible to derive explicitly a parametrization for the fast variables that translates into deterministic, stochastic and non-Markovian extra terms in the equations of motion for the variables of interest. We show that our approach is computationally parsimonious and has great flexibility, as it is explicitly scale-adaptive, and we prove that it is competitive compared with empirical ad-hoc approaches. While the parametrization proposed here is universal and can easily be adapted analytically to changes in parameter values by a simple rescaling procedure, the parametrization constructed with the ad-hoc approach needs to be recomputed each time the parameters of the systems are changed. The price we pay for the higher flexibility of the method proposed here is having a lower accuracy in each individual case.

Keywords: parametrization, multiscale systems, stochastic dynamics, memory, noise, response theory, chaos, scale-adaptivity

Read: Vissio, G., & Lucarini, V. (2018). A proof of concept for scale-adaptive parametrizations: the case of the Lorenz '96 model. Quarterly Journal of the Royal Meteorological Society, 144, 63-75. doi:10.1002/qj.3184.

Online: https://doi.org/10.1002/qj.3184

Contact: Gabriele Vissio (gabirele.vissiodummy@uni-hamburgdummy2.de)

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Date issued: December 2017

Hindcast skill for the Atlantic meridional overturning circulation at 26.5° N within two MPI-ESM decadal climate prediction systems

We analyse the hindcast skill for the Atlantic meridional overturning circulation (AMOC) against 10 years of RAPID/MOCHA AMOC observations, which are now long enough to remove the mean seasonal cycle prior to the hindcast skill analysis. We analyse AMOC hindcast skill in two hindcast ensembles generated with two differently initialised decadal prediction systems that are both based on the earth system model MPI-ESM. We evaluate the hindcast skill for the AMOC and its components in both prediction systems against RAPID/MOCHA observations both with and without the mean seasonal cycle removed using anomaly correlation (COR) and root-mean-square error as skill measures. We find significant hindcast skill for most lead years up to 5 for monthly-mean AMOC variations only in the newer of the two prediction systems and only using COR, but with and without the mean seasonal cycle removed. In both systems and for all analysed lead years, the two geostrophic transport components (the upper-mid-ocean transport and Florida Strait combined, that is: AMOC minus Ekman) are the main source of hindcast skill. In the present model setup and with the currently available observational time series, we cannot relate AMOC hindcast skill to the upper-mid-ocean transport alone. Yet, we can show that the seasonal variability of the upper-mid-ocean transport in the free coupled model originates from eastern boundary density variability. Overall, our results indicate modest yet robust AMOC hindcast skill above the uninitialized simulation, independent of the treatment of the seasonal cycle, although we cannot directly link this hindcast skill to the initialisation of the density field with either initialisation method.

Keywords: Decadal predictions, Meridional overturning circulation, Hindcast skill

Read: Müller, V., Pohlmann, H., Düsterhus, A., Matei, D., Marotzke, J., Müller, W. A., Zeller, M., & Baehr, J. (2017). Hindcast skill for the Atlantic meridional overturning circulation at 26.5° N within two MPI-ESM decadal climate prediction systems. Climate Dynamics, 49, 2975-2990. doi:10.1007/s00382-016-3482-z.

Online: https://doi.org/10.1007/s00382-016-3482-z

Contact: Jürgen Scheffran (juergen.scheffrandummy@uni-hamburgdummy2.de)

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Date Issued: December 2017

Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe

This study introduces a new approach to investigate the potential effects of air-sea coupling on simulated precipitation inland over Central Europe. We present an inter-comparison of two regional climate models (RCMs), namely, the COSMO-CLM (hereafter CCLM) and RCA4 models, which are configured for the EURO-CORDEX domain in the coupled and atmosphere-only modes. Two versions of the CCLM model, namely, 4.8 and 5.0, join the inter-comparison being almost two different models while providing pronouncedly different summer precipitation simulations because of many changes in the dynamics and physics of CCLM in version 5.0. The coupling effect on the prominent summer dry bias over Central Europe is analysed using seasonal (JJA) mean statistics for the 30-year period from 1979 to 2009, with a focus on extreme precipitation under specific weather regimes. The weather regimes are compared between the coupled and uncoupled simulations to better understand the mechanism of the coupling effects. The comparisons of the coupled systems with the atmosphere-only models show that coupling clearly reduces the dry bias over Central Europe for CCLM 4.8, which has a large dry summer bias, but not for CCLM 5.0 and RCA4, which have smaller dry biases. This result implies that if the atmosphere-only model already yields reasonable summer precipitation over Central Europe, not much room for improvement exists that can be caused by the air-sea coupling over the North Sea and the Baltic Sea. However, if the atmosphere-only model shows a pronounced summer dry bias because of a lack of moisture transport from the seas into the region, the considered coupling may create an improved simulation of summer precipitation over Central Europe, such as for CCLM 4.8. For the latter, the benefit of coupling varies over the considered timescales. The precipitation simulations that are generated by the coupled system COSTRICE 4.8 and the atmosphere-only CCLM 4.8 are mostly identical for the summer mean. However, the COSTRICE simulations are generally more accurate than the atmosphere-only CCLM simulations if extreme precipitation is considered, particularly under Northerly Circulation conditions, in which the airflow from the North Atlantic Ocean passes the North Sea in the coupling domain. The air-sea feedback (e.g., wind, evaporation and sea surface temperature) and land-sea interactions are better reproduced with the COSTRICE model system than the atmosphere-only CCLM and lead to an improved simulation of large-scale moisture convergence from the sea to land and, consequently, increased heavy precipitation over Central Europe.

Keywords: Regional climate model, Central Europe, EURO-CORDEX, Dry bias, Extreme precipitation, Air-sea coupling

Read: Ho-Hagemann, H. T. M., Groeger, M., Rockel, B., Zahn, M., Geyer, B., & Meier, H. E. M. (2017). Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe. Climate Dynamics, 49, 3851-3876. doi:10.1007/s00382-017-3546-8.

Online: https://doi.org/10.1007/s00382-017-3546-8

Contact: Matthias Zahn (matthias.zahndummy@hzgdummy2.de)

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Date issued: December 2017

Why is scaling important?

Scaling is an emerging concept for understanding climate variability on all timescales. Here, we introduce the concept of scaling and discuss its importance for climate studies. We also discuss possible mechanisms for the emergence of scaling in the climate system.

Read: Franzke, C., & Yuan, N. (2017). Why is scaling important? Centennial to Millennial Climate Variability, 25(3), 134-135. doi:10.22498/pages.25.3.134.

Online: https://doi.org/10.22498/pages.25.3.134

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

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Date issued: December 2017

Centennial climate change: The unknown variability zone

Read: Crucifix, M., de Vernal, A., & Franzke, C. (2017). Centennial climate change: The unknown variability zone. Centennial to Millennial Climate Variability, 25(3), 133. doi:10.22498/pages.25.3.133.

Online: https://doi.org/10.22498/pages.25.3.133

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

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Date issued: December 2017

Centennial to Millennial Climate Variability

This issue of Past Global Changes Magazine “Centennial to Millennial Climate Variability" shows how recent progress in our knowledge of past climates led us to revisit our ideas about the spectrum of natural climate variability. Contributions highlight the concept of scaling laws, but also warn about pitfalls of paleoclimate timeseries analysis. It is a product of PAGES' Climate Variability Across Scales (CVAS) working group.

Read: Crucifix, M., de Vernal, A., Franzke, C., & von Gunten, L. (Eds.). (2017). Centennial to Millennial Climate Variability [Special Issue].  Past Global Changes Magazine, 25(3),. doi:10.22498/pages.25.3.

Online: https://doi.org/10.22498/pages.25.3

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

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Date issued: December 2017

The relationship between the Madden-Julian oscillation and the land surface soil moisture

The impact of the Madden–Julian oscillation (MJO) on the global land surface soil moisture was explored in the study. The MJO index was calculated from long term 1997–2013 GPCP precipitation and ERA-Interim 850-hPa and 250-hPa zonal winds. The composites of soil moisture anomalies over eight MJO phases were mapped and analyzed. In order to distinguish the MJO signal with other patterns of climate variability, only MJO event days are used in the composites. In addition, the statistical significance of the anomaly composites is estimated using the Student's t-test. The MJO has been found to be the prominent source of the intraseasonal variation of the monsoon systems, which induces the variations of precipitation. Our results show that the variation of soil moisture between MJO phases also agrees well with the variation of the monsoon systems. In addition to the monsoon regions, the MJO also affects soil moisture over other areas such as East Africa. The relation between the soil moisture and precipitation anomaly composites across the MJO phases was also investigated. The results show that the variation of soil moisture over MJO phases is related to its connection to precipitation. In addition, large similarities were found between the GPCP-derived MJO index and the corresponding ESA CCI soil moisture composites, and ERA-Interim-derived MJO index and corresponding ERA-Interim soil moisture composites. This proves the feasibility of ERA-Interim datasets for MJO related studies. Owing to the different resolutions of the CCI and ERA-Interim soil moisture, CCI is more appropriate for regional and ERA-Interim dataset for large-scale MJO related analysis.

Keywords: Madden–Julian oscillation, CCI soil moisture, GPCP precipitation, ERA-interim, Intraseasonal variation, Soil moisture and precipitation relationship

Read: Peng, J., Loew, A., & Crueger, T. (2017). The relationship between the Madden-Julian oscillation and the land surface soil moisture. Remote Sensing of Environment, 2013, 226-239. doi:10.1016/j.rse.2017.07.004.

Online: https://doi.org/10.1016/j.rse.2017.07.004

Contact: Traute Crüger (traute.cruegerdummy@mpimet.mpgdummy2.de)

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Date issued: December 2017

Noise performance of microwave humidity sounders over their lifetime

The microwave humidity sounders Special Sensor Microwave Water Vapor Profiler (SSMT-2), Advanced Microwave Sounding Unit-B (AMSU-B) and Microwave Humidity Sounder (MHS) to date have been providing data records for 25 years. So far, the data records lack uncertainty information essential for constructing consistent long time data series. In this study, we assess the quality of the recorded data with respect to the uncertainty caused by noise. We calculate the noise on the raw calibration counts from the deep space views (DSVs) of the instrument and the noise equivalent differential temperature (NEΔT) as a measure for the radiometer sensitivity. For this purpose, we use the Allan deviation that is not biased from an underlying varying mean of the data and that has been suggested only recently for application in atmospheric remote sensing. Moreover, we use the bias function related to the Allan deviation to infer the underlying spectrum of the noise. As examples, we investigate the noise spectrum in flight for some instruments. For the assessment of the noise evolution in time, we provide a descriptive and graphical overview of the calculated NEΔT over the life span of each instrument and channel. This overview can serve as an easily accessible information for users interested in the noise performance of a specific instrument, channel and time. Within the time evolution of the noise, we identify periods of instrumental degradation, which manifest themselves in an increasing NEΔT, and periods of erratic behaviour, which show sudden increases of NEΔT interrupting the overall smooth evolution of the noise. From this assessment and subsequent exclusion of the aforementioned periods, we present a chart showing available data records with NEΔT  <  1 K. Due to overlapping life spans of the instruments, these reduced data records still cover without gaps the time since 1994 and may therefore serve as a first step for constructing long time series. Our method for count noise estimation, that has been used in this study, will be used in the data processing to provide input values for the uncertainty propagation in the generation of a new set of Fundamental Climate Data Records (FCDRs) that are currently produced in the project "Fidelity and Uncertainty in Climate data records from Earth Observation (FIDUCEO)".

Read: Hans, I., Burgdorf, M., John, V. O., Mittaz, J., & Buehler, S. A. (2017). Noise performance of microwave humidity sounders over their lifetime. Atmospheric Measurement Techniques, 10, 4927-4945. doi:10.5194/amt-10-4927-2017.

Online: https://doi.org/10.5194/amt-10-4927-2017

Contact: Imke Hans (imke.hansdummy@uni-hamburgdummy2.de)

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Date issued: December 2017

How Robust Is the Weakening of the Pacific Walker Circulation in CMIP5 Idealized Transient Climate Simulations?

The tropical overturning circulations are likely weakening under increased CO2 forcing. However, insufficient understanding of the circulations’ dynamics diminishes the full confidence in such a response. Based on a CMIP5 idealized climate experiment, this study investigates the changes in the Pacific Walker circulation under anthropogenic forcing and the sensitivity of its weakening response to internal variability, general circulation model (GCM) configuration, and indexing method. The sensitivity to internal variability is analyzed by using a 68-member ensemble of the MPI-ESM-LR model, and the influence of model physics is analyzed by using the 28-member CMIP5 ensemble. Three simple circulation indices—based on mean sea level pressure, 500-hPa vertical velocity, and 200-hPa velocity potential—are computed for each member of the two ensembles. The study uses the output of the CMIP5 idealized transient climate simulations with 1% yr−1 CO2 increase from preindustrial level, and investigates the detected circulation response until the moment of CO2 doubling (70 yr). Depending on the indexing method, it is found that 50%–93% of the MPI-ESM-LR and 54%–75% of the CMIP5 ensemble members project significant negative trends in the circulation’s intensity. This large spread in the ensembles reduces the confidence that a weakening circulation is a robust feature of climate change. Furthermore, the similar magnitude of the spread in both ensembles shows that the Walker circulation response is strongly influenced by natural variability, even over a 70-yr period.

Keywords: Walker circulation; Anthropogenic effects; Model comparison

Read: Plesca, E., Buehler, S. A., & Grützun, V. (2017). How Robust Is the Weakening of the Pacific Walker Circulation in CMIP5 Idealized Transient Climate Simulations? Journal of Climate, 31(1), 81-97. doi:10.1175/JCLI-D-17-0151.1.

Online: https://doi.org/10.1175/JCLI-D-17-0151.1

Contact: Elina Plesca (plesca.elinadummy@uni-hamburgdummy2.de)

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Date issued: December 2017

Nonlocality of Tropical Cyclone Activity in Idealized Climate Simulations

The response of tropical cyclone activity in the predicted warmer future climate is still a topic of scientific research. However, by the nonlocality hypothesis, tropical cyclone activity depends rather on relative than absolute sea surface temperature (SST). This hypothesis is investigated through idealized experiments performed with the global atmospheric climate model PlaSim. The model includes a prescribed SST and adopts a spectral resolution of T170 for resolving tropical cyclones. An idealized land-sea configuration with two oceans and two continents has been used to study the nonlocality mechanism. The sensitivity experiments WARMBASIN and COLDBASIN include a positive and negative SST anomaly of 2.5 K in the northeastern basin. The tropical cyclone activity in the control run is similar in all four ocean basins while experiment WARMBASIN simulates a striking local increase of tropical cyclones. However, they nearly vanish in the other three ocean basins. The response is weaker and in the opposite way in COLDBASIN with a local reduction and a nonlocal increase. Analysis of well-known cyclogenesis indices shows that nonlocality could be explained by the vorticity, relative humidity, and upper tropospheric temperature changes in experiment WARMBASIN while only vorticity is in agreement with nonlocality in experiment COLDBASIN. The vorticity anomalies determine the presence or absence of a steady state large-scale low at the location where tropical cyclones favorably form. This low is modified by an SST-induced change of a Walker-like planetary circulation.

Read: Frisius, T., & Abdullah, S. (2017). Nonlocality of Tropical Cyclone Activity in Idealized Climate Simulations. Journal of Advances in Modeling Earth Systems, 9, 3099-3115. doi:10.1002/2017MS001084.

Online: https://doi.org/10.1002/2017MS001084

Contact: Thomas Frisius (thomas.frisiusdummy@uni-hamburgdummy2.de)

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Date issued: December 2017

A Global Data Analysis for Representing Sediment and Particulate Organic Carbon Yield in Earth System Models

Although sediment yield (SY) from water erosion is ubiquitous and its environmental consequences are well recognized, its impacts on the global carbon cycle remain largely uncertain. This knowledge gap is partly due to the lack of soil erosion modeling in Earth System Models (ESMs), which are important tools used to understand the global carbon cycle and explore its changes. This study analyzed sediment and particulate organic carbon yield (CY) data from 1,081 and 38 small catchments (0.1–200 km2), respectively, in different environments across the globe. Using multiple statistical analysis techniques, we explored environmental factors and hydrological processes important for SY and CY modeling in ESMs. Our results show clear correlations of high SY with traditional agriculture, seismicity and heavy storms, as well as strong correlations between SY and annual peak runoff. These highlight the potential limitation of SY models that represent only interrill and rill erosion because shallow overland flow and rill flow have limited transport capacity due to their hydraulic geometry to produce high SY. Further, our results suggest that SY modeling in ESMs should be implemented at the event scale to produce the catastrophic mass transport during episodic events. Several environmental factors such as seismicity and land management that are often not considered in current catchment-scale SY models can be important in controlling global SY. Our analyses show that SY is likely the primary control on CY in small catchments and a statistically significant empirical relationship is established to calculate SY and CY jointly in ESMs.

Read: Hartmann, J., Tan, Z., Leung, L. R., Li, H., Tesfa, T., Vanmaercke, M., Poesen, J., Zhang, X., & Lu, H. (2017). A Global Data Analysis for Representing Sediment and Particulate Organic Carbon Yield in Earth System Models. Water Resources Research, 53(12), 10674-10700. doi:10.1002/2017WR020806.

Online: https://doi.org/10.1002/2017WR020806

Contact: Jens Hartmann (jens.hartmanndummy@uni-hamburgdummy2.de)

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Date issued: October 2017

Regional sea level variability and trends, 1960–2007: A comparison of sea level reconstructions and ocean syntheses

Abstract: Several existing statistical and dynamical reconstructions of past regional sea level variability and trends are compared with each other and with tide gauges over the 48 year period 1960–2007, partially predating the satellite altimetry era. Evaluated statistical reconstructions were built from tide‐gauge data (TGR), and dynamical reconstructions from ocean data assimilation (ODA) approaches. Although most of the TGRs yield global‐mean time series of sea level with trends deviating within only ±0.1 mm yr−1, the spatial anomalies of the trends deviate substantially between the reconstructions over the period predating altimetry. In contrast, TGRs match observed regional trend patterns fairly well during the satellite altimetry era. TGRs match tide‐gauge data better than ODA results; however, they exhibit less variability in the open ocean compared to altimetric data. Over the prealtimetry period, all reconstructed regional sea level trend patterns deviate substantially from each other. In terms of detrended correlations in this earlier period, the reconstructions match tide gauges, and each other, much better in the Pacific than in the Atlantic. An ensemble of all TGR and ODA estimates provides some improvements in correlations and trends to both tide gauges and altimetry. Nevertheless, a lack of independent open ocean sea surface height data predating altimetry makes impossible the validation of the ensemble for prealtimetry open ocean sea level trends and variability. Estimating regional sea level changes prior to altimetry therefore remains an unsolved challenge.

Keywords: sea level reconstruction, historical climate data, sea level variability and trends

Read: Carson, M., Köhl, A., Stammer, D., Meyssignac, B., Church, J., Schröter, J,Wenzel, M., & Hamlington, B. (2017). Regional sea level variability and trends, 1960–2007: A comparison of sea level reconstructions and ocean syntheses. Journal of Geophysical Research: Oceans, 122, 9068–9091. doi.10.1002/2017JC012992

Online: https://doi.org/10.1002/2017JC012992

Contact: Mark Carson (mark.carsondummy@uni-hamburgdummy2.de)

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Date Issued: October 2017

Evolution in temperature-dependent phytoplankton traits revealed from a sediment archive: do reaction norms tell the whole story?

Abstract: The high evolutionary potential of phytoplankton species allows them to rapidly adapt to global warming. Adaptations may occur in temperature-dependent traits, such as growth rate, cell size and life cycle processes. Using resurrection experiments with resting stages from living sediment archives, it is possible to investigate whether adaptation occurred. For this study, we revived resting cysts of the spring bloom dinoflagellate Apocalathium malmogiense from recent and 100-year-old sediment layers from the Gulf of Finland, and compared temperature-dependent traits of recent and historic strains along a temperature gradient. We detected no changes in growth rates and cell sizes but a significant difference between recent and historic strains regarding resting cyst formation. The encystment rate of recent strains was significantly lower compared with historic strains which we interpret as an indication of adaptation to higher and more rapidly increasing spring temperatures. Low encystment rates may allow for bloom formation even if the threshold temperature inducing a loss of actively growing cells through resting cyst formation is exceeded. Our findings reveal that phenotypic responses of phytoplankton to changing temperature conditions may include hidden traits such as life cycle processes and their regulation mechanisms. This study emphasizes the potential of living sediment archives to investigate plankton responses and adaptation to global warming.

Keywords: adaptation; global warming; phytoplankton; sediment archives; temperature-dependent traits

Read: Hinners J, Kremp A, Hense I (2017): Evolution in temperature-dependent phytoplankton traits revealed from a sediment archive: do reaction norms tell the whole story? Proceedings of the Royal Society B: Biological Sciences 284 (1864), 20171888. doi.10.1098/rspb.2017.1888

Online: https://doi.org/10.1098/rspb.2017.1888

Contact: Jana Hinners (jana.hinnersdummy@uni-hamburgdummy2.de)

A.  Reviewed Publications

1.    Forthcoming: Frank, A. M., Froese, R. E. M., Hof, B. C., Scheffold, M. I. E., Schreyer, F., Zeller, M., & Rödder, S. (forthcoming). Riding alone on the elevator – a class experiment in interdisciplinary education. Learning and Teaching: The International Journal of Higher Education in the Social Sciences.

2.    Issued 2017: Rasche, L. and Taylor, R.A.J. (2017), 'A pest submodel for use in integrated assessment models', Transactions of the ASABE, 60 (1), 147-58. https://doi.org/10.13031/trans.11931

3.    Issued 2017: Brüggemann, Michael (2017): Post-normal journalism: Climate journalism and its changing contribution to an unsustainable debate. In Peter Berglez, Ulrika Olausson, M. Ots (Eds.): What is Sustainable Journalism? Integrating the Environmental, Social, and Economic Challenges of Journalism. New York: Peter Lang. http://dx.doi.org/10.3726/b11462

4.    Issued 2017: Vetter, M., & Olbrich, S. (n.d.). Development and integration of an in-situ framework for visualization of large-scale, unsteady phenomena in ICON. Journal of Supercomputing Frontiers and Innovations. http://dx.doi.org/10.14529/jsfi170303

5.    Issued December 2017: Ge, F., Sielmann, F., Zhu, X. et al. Clim Dyn (2017). The link between Tibetan Plateau monsoon and Indian summer precipitation: a linear diagnostic perspective.
doi:10.1007/s00382-017-3585-1

6.    Issued December 2017: Ho-Hagemann, H. T. M., Groeger, M., Rockel, B., Zahn, M., Geyer, B., & Meier, H. E. M. (2017). Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe. Climate Dynamics, 49, 3851–3876. http://doi.org/10.1007/s00382-017-3546-8

7.    Issued December 2017: C Juretzek, C Hadziioannou (2017) Linking source region and ocean wave parameters with the observed primary microseismic noise, Geophysical Journal International, Volume 211, Issue 3, 1 December 2017, Pages 1640–1654. https://doi.org/10.1093/gji/ggx388

8.    Issued November 2017: Stammer, D., & Griffies, S. M. (2017). Ocean Modeling and Data Assimilation in the Context of Satellite Altimetry. In D. Stammer & A. Cazenave (Eds.), Satellite Altimetry Over Oceans and Land Surfaces. Boca Raton, FL: Taylor & Francis. https://www.taylorfrancis.com/books/9781498743464

9.    Issued November 2017: Barcikowska, M., Feser, F., Zhang, W., & Mei, W. (2017). Changes in intense tropical cyclone activity for the western North Pacific during the last decades derived from a regional climate model simulation. Climate Dynamics, 49, 2931–2949. http://doi.org/10.1007/s00382-016-3420-0

10. Issued November 2017: Große, F., Kreus, M., Lenhart, H.-J., Pätsch, J., & Pohlmann, T. (2017). A novel modeling approach to quantify the influence of nitrogen inputs on the oxygen dynamics of the North Sea. Frontiers in Marine Science, 4. http://doi.org/10.3389/fmars.2017.00383

11. Issued November 2017: Karabil, S., Zorita, E., & Baehr, J. (2017). Mechanisms of variability in decadal sea-level trends in the Baltic Sea over the 20th century. Earth System Dynamics, (8), 1031–1046. PhD Thesis. http://doi.org/10.5194/esd-8-1031-2017

12. Issued November 2017: Müller, V., Pohlmann, H., Düsterhus, A., Matei, D., Marotzke, J., Müller, W. A., … Baehr, J. (2017). Hindcast skill for the Atlantic meridional overturning circulation at 26.5° N within two MPI-ESM decadal climate prediction systems. Climate Dynamics, 49, 2975–2990. http://doi.org/10.1007/s00382-016-3482-z

13. Issued November 2017: Stammer, D., & Cazenave , A. (2017). Satellite altimetry over oceans and land surfaces. Boca Raton, FL: Taylor & Francis. https://www.taylorfrancis.com/books/9781498743464

14. Issued November 2017: Weder, C., Müller, G., & Brümmer, B. (2017). Precipitation extremes on time scales from minute to month measured at the Hamburg Weather Mast 1997-2014 and their relation to synoptic weather types. Meteorologische Zeitschrift. http://doi.org/10.1127/metz/2017/0812

15. Issued October 2017: Augustin, J., Horstmann, R., Homeier-Bachmann, T., Jensen, K., Knieling, J., Krefis, A., … Strube, C. (2018). Gesundheit. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Springer Spektrum. https://doi.org/10.1007/978-3-662-55379-4_8

16. Issued October 2017: Barlow, J., Best, M., Bohnenstengel, S. I., Clark, P., Grimmond, S., Lean, H., … Zhong, J. ( 2017). Developing a research strategy to better understand, observe, and simulate urban atmospheric processes at kilometer to subkilometer scales. Bulletin of the American Meteorological Society, 98, ES261–ES264. http://doi.org/10.1175/BAMS-D-17-0106.1

17. Issued October 2017: Bechtel, B., Zakšek, K., Oßenbrügge, J., Kaveckis, G., & Böhner, J. (2017). Towards a satellite based monitoring of urban air temperatures. Sustainable Cities and Society, 34, 22–31. http://doi.org/10.1016/j.scs.2017.05.018

18. Issued October 2017: Brüggemann, M., De Silva-Schmidt, F., Hoppe, I., Arlt, D., & Schmitt, J. B. (2017). The appeasement effect of a United Nations climate summit on the German public. Nature Climate Change, 7, 783–787. http://doi.org/10.1038/nclimate3409

19. Issued October 2017: Brüggemann, M., Neverla, I., Hoppe, I., & Walter, S. (2018). Klimawandel in den Medien. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg (pp. 243–254 ). Springer Spektrum.
https://doi.org/10.1007/978-3-662-55379-4_12

20. Issued October 2017: Brzoska, M., Oßenbrügge, J., Fröhlich, C., & Scheffran, J. (2018). Migration. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg (pp. 209–224). Berlin: Springer Spektrum. http://doi.org/10.1007_978-3-662-55379-4_10

21. Issued October 2017: Engels, A., Wickel, M., Knieling, J., Kretschmann, N., & Walz, K. (2018). Lokale Klima-Governance im Mehrebenensystem: formale und informelle Regelungsformen. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Springer Spektrum.
https://doi.org/10.1007/978-3-662-55379-4_14

22. Issued October 2017: Groth M, M., & Rose, J. (2018). Infrastrukturen (Energie- und Wasserversorgung). In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Springer Spektrum.
https://doi.org/10.1007/978-3-662-55379-4_9

23. Issued October 2017: Klein, B., Klein, H., Loewe, P., Möller, J., Müller-Navarra, S., Holfort, J., … Seiffert, R. (2018). Deutsche Bucht mit Tideelbe und Lübecker Bucht. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Springer Spektrum. https://doi.org/10.1007/978-3-662-55379-4_4 

24. Issued October 2017: Köhl, M., Möllmann, C., Fromm, J., Kraus, G., & Mues, V. (2018). Land- und Forstwirtschaft, Fischerei. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Springer Spektrum.
https://doi.org/10.1007/978-3-662-55379-4_7

25. Issued October 2017: Meinke, I., Rechid , D., Tinz , B., Maneke, M., Lefebvre, C., & Isokeit, E. (2018). Klima der Region – Zustand, bisherige Entwicklung und mögliche Änderungen bis 2100. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Springer Spektrum. https://doi.org/10.1007/978-3-662-55379-4_2 

26. Issued October 2017: Ratter, B. (2018). Wahrnehmung des Klimawandels in der Metropolregion Hamburg. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg (pp. 255–264). Springer Spektrum.
https://doi.org/10.1007/978-3-662-55379-4_13

27. Issued October 2017: Schaaf, B., von Storch, H., & Feser, F. (2017). Does spectral nudging have an effect on dynamical downscaling applied in small regional model domains? Monthly Weather Review, 145, 4303–4311. http://doi.org/10.1175/MWR-D-17-0087.1

28. Issued October 2017: Schickhoff, U., & Eschenbach, A. (2018). Terrestrische und semiterrestrische Ökosysteme. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg (pp. 109–145). Berlin: Springer Spektrum.
http://doi.org/10.1007_978-3-662-55379-4_6

29. Issued October 2017: Schlünzen, H., Riecke, W., Bechtel, B., Boettcher , M., Buchholz, S., Grawe, D., … Wiesner, S. (2018). Stadtklima in Hamburg. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg (pp. 37–53). Berlin: Springer Spektrum. https://doi.org/10.1007/978-3-662-55379-4_3

30. Issued October 2017: Von Storch, H., Meinke, I., & Claussen, M. (2018a). Einleitung und Zusammenfassung. In H. von Storch, I. Meinke, & M. Claussen (Eds.), Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg (pp. 1–11). Springer Spektrum. http://doi.org/10.1007/978-3-662-55379-4_1

31. Issued October 2017: Von Storch, H., Meinke, I., & Claussen, M. (Eds.). (2018b). Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg. Berlin: Springer Spektrum.
http://doi.org/10.1007/978-3-662-55379-4

32. Issued September 2017: Beckmann, A., & Hense, I. (2017). The impact of primary and export production on the formation of the secondary nitrite maximum: A model study. Ecological Modelling, 359, 25-33. https://doi.org/10.1016/j.ecolmodel.2017.05.014

33. Issued September 2017: Beermann, F., Langer, M., Wetterich, S., Strauss, J., Boike, J., Fiencke, C., … Kutzbach, L. (2017). Permafrost thaw and liberation of inorganic nitrogen from polygonal tundra soils in eastern Siberia. Permafrost and Periglacial Processes, 28, 605–618. http://doi.org/10.1002/ppp.1958

34. Issued September 2017: G. Conti and G. Badin (2017), "Hyperbolic Covariant Coherent Structures in Two-Dimensional Flows", Fluids, 2, 50. http://www.mdpi.com/2311-5521/2/4/50

35. Issued September 2017: Hartmann, J., Li, G., & West, A. J. (2017). Running out of gas: Zircon 18O-Hf-U/Pb evidence for Snowball Earth preconditioned by low degassing. Geochemical Perspective Letters, 4, 41–46. http://doi.org/10.7185/geochemlet.1734 

36. Issued September 2017: Karabil, S. (2017). Influence of Atmospheric Circulation on the Baltic Sea Level Rise under the RCP8.5 Scenario over the 21st Century. Climate, 5. http://doi.org/10.3390/cli5030071

37. Issued September 2017: Loew, A., Bell, W., Brocca, L., Bulgin, C. E., Burdanowitz, J., Calbet, X., … Verhoelst, T. (2017). Validation practices for satellite based earth observation data across communities. Reviews of Geophysics, 55, 779–817. http://doi.org/10.1002/2017RG000562

38. Issued September 2017: Neumann, H., Diekmann, R., Emeis, K., Kleeberg, U., Moll, A., & Kröncke, I. (2017). Full-coverage spatial distribution of epibenthic communities in the south-eastern North Sea in relation to habitat characteristics and fishing effort. Marine Environmental Research. http://doi.org/10.1016/j.marenvres.2017.07.010

39. Issued September 2017: Neumann, A., van Beusekom, J. E. E., Holtappels, M., & Emeis, K. (September 2017) Nitrate consumption in sediments of the German Bight (North Sea). Journal of Sea Research. http://doi.org/10.1016/j.seares.2017.06.012

40. Issued September 2017: Pollmann, F., Eden, C., & Olbers, D. (2017). Evaluating the global internal wave model IDEMIX using finestructure methods. Journal of Physical Oceanography. http://doi.org/10.1175/JPO-D-16-0204.1

41. Issued September 2017: Strauss, J., Schirrmeister, L., Grosse, G., Fortier, D., Hugelius, G., Knoblauch, C., … Veremeeva, A. (2017). Deep Yedoma permafrost: A synthesis of depositional characteristics and carbon vulnerability. Earth-Science Reviews, 172 , 75–86. http://doi.org/10.1016/j.earscirev.2017.07.007

42. Issued August 2017: Badin, G., & Crisciani, F. (2018). Variational Formulation of Fluid and Geophysical Fluid Dynamics - Mechanics, Symmetries and Conservation Laws. Heidelberg : Springer Int. Publ. http://doi.org/10.1007/978-3-319-59695-2

43. Issued August 2017: Böhner, J. & Bechtel, B. (2017): GIS in Climatology and Meteorology. – In: Huang, B. [Ed.]: Comprehensive Geographic Information Systems. – Elsevier (in press). https://www.elsevier.com/books/comprehensive-geographic-information-systems/huang/978-0-12-804660-9

44. Issued August 2017: Köhl, M., Neupane, P. R., & Lotfiomran, N. (2017). The impact of tree age on biomass growth and carbon accumulation capacity: A retrospective analysis using tree ring data of three tropical tree species grown in natural forests of Suriname. PLoS One, 12, 1–17. http://doi.org/10.1371/journal.pone.0181187

45.  Issued August 2017: Liu, X., Köhl, A., & Stammer, D. (2017). Dynamical ocean response to projected changes of the global water cycle. Journal of Geophysical Research: Oceans , 122, 1–22. http://doi.org/10.1002/2017JC013061

46. Issued August 2017: Moreno-Chamarro, E., Zanchettin, D., Lohmann, K., Luterbacher, J., & Jungclaus, J. H. (2017). Winter amplification of the European Little Ice Age cooling by the subpolar gyre. Scientific Reports, 7. http://doi.org/10.1038/s41598-017-07969-0

47. Issued August 2017: Nyawira, S.-S., Nabel, J. E. M. S., Brovkin, V., & Pongratz, J. (2017). Input-driven versus turnover-driven controls of simulated changes in soil carbon from land-use change. Environmental Research Letters, 12(8). http://doi.org/10.1088/1748-9326/aa7ca9

48. Issued August 2017: Pätsch, J., Burchard, H., Dieterich, C., Gräwe , U., Gröger, M., Mathis, M., … Eden, C. (2017). An evaluation of the North Sea circulation in global and regional models relevant for ecosystem simulations. Ocean Modelling, 116, 70–95. http://doi.org/10.1016/j.ocemod.2017.06.005

49. Issued August 2017: Von Storch, H., Feser, F., Geyer, B., Klehmet, K., Li D., Rockel, B., … Zorita, E. (2017). Regional reanalysis without local data: exploiting the downscaling paradigm. Journal of Geophysical Research-Atmospheres, 122, 8631–8649. http://doi.org/10.1002/2016JD026332

50. Issued August 2017: Zscheischler, J., Mahecha, M. D., Avitabile, V., Calle, L., Carvalhais, N., Ciais, P., … Reichstein, M. (2017). Reviews and syntheses: An empirical spatiotemporal description of the global surface–atmosphere carbon fluxes: opportunities and data limitations. Biogeosciences, 14, 3685–3703. http://doi.org/10.5194/bg-14-3685-2017

51. Issued July 2017: Di Lallo, G., Mundhenk, P., Marchetti, M., & Köhl, M. (2017). Understanding Measurement Reporting and Verification Systems for REDD+ as an Investment for Generating Carbon Benefits. Forests, 8, 271–289. http://doi.org/10.3390/f8080271

52. Issued July 2017: Karki, R., Hasson, S., Gerlitz, L., Schickhoff, U., Scholten, T. & Böhner, J. (2017): Quantifying the added value of high resolution climate models: A systematic comparison of WRF simulations for complex Himalayan terrain. – Earth System Dynamics Discussion. doi:10.5194/esd-2017-31

53. Issued July 2017: Karki, R., ul Hasson, S., Gerlitz, L., Schickhoff, U., Scholten, T., and Böhner, J. (2017). Quantifying the added value of convection-permitting climate simulations in complex terrain: a systematic evaluation of WRF over the Himalayas, Earth Syst. Dynam., 8, 507-528. https://doi.org/10.5194/esd-8-507-2017

54. Issued July 2017: Walz, J., Knoblauch, C., Böhme, L., & Pfeiffer, E.-M. (2017). Regulation of soil organic matter decomposition in permafrost-affected Siberian tundra soils - Impact of oxygen availability, freezing and thawing, temperature, and labile organic matter. Soil Biology and Biochemistry, 110, 34–43. http://doi.org/10.1016/j.soilbio.2017.03.001

55. Issued July 2017: Yang L.E., Hoffmann P., Scheffran J. (2017): Health impacts of smog pollution: Understanding the human dimensions of exposure. The Lancet Planetary Health 1:e132 - e133. http://dx.doi.org/10.1016/S2542-5196(17)30067-0

56. Issued June 2017: Barcikowska, M. J., Kapnick, S. B., & Feser, F. (2017). Impact of large-scale circulation changes in the North Atlantic sector on the current and future Mediterranean winter hydroclimate. Climate Dynamics. http://doi.org/10.1007/s00382-017-3735-5

57. Issued June 2017: Burdanowitz, J., Klepp, C., Bakan, S., & Bühler, S. (2017). Simulation of ship-track versus satellite-sensor differences in oceanic precipitation using an island-based radar. Remote Sensing, 9(Spec. Iss: Remote Sensing Precipitation Measurement, Validation, and Applications). http://doi.org/10.3390/rs9060593

58. Issued June 2017: Ghosh, R., Müller, W. A., Baehr, J., & Bader, J. (2017). Impact of observed North Atlantic multidecadal variations to European summer climate: a linear baroclinic response to surface heating. Climate Dynamics, 38, 3547–3563. http://doi.org/10.1007/s00382-016-3283-4

59. Issued June 2017: Itkin, P., Spreen, G., Cheng, B., Doble, M., Girard-Ardhuin, F., Haapala, J., … Wilkinson, J. (2017). Thin ice and storms: Sea ice deformation from buoy arrays deployed during N-ICE2015. Journal of Geophysical Research: Oceans, 122, 4661–4674. http://doi.org/10.1002/2016JC012403

60. Issued June 2017: Neumann, M., Mues, V., Moreno, A., Hasenauer, H., & Seidl, R. (2017). Climate variability drives recent tree mortality in Europe. Global Change Biology. http://doi.org/10.1111/gcb.13724

61. Issued June 2017: Njoroge, J. M., Ratter, B., & Atieno, L. (2017). Climate change policy making process in Kenya: deliberative inclusionary processes in play. International Journal of Climate Change Strategies and Management, 9, 535–554. http://doi.org/10.1108/IJCCSM-10-2016-0154

62. Issued June 2017: Petzold, J., Ratter, B., & Holdschlag, A. (2017). Competing knowledge systems and adaptability to sea-level rise in The Bahamas. Area. http://doi.org/10.1111/area.12355

63. Issued June 2017: Stammer, D., Bracco, A., & Detemmerman, V. (2017). Climate and Ocean Science Builds for the Future. EOS, 98. http://doi.org/10.1029/2017EO073225

64. Issued June 2017: Suarez-Gutierrez, L., Li, C., Thorne, P., & Marotzke, J. (2017). Internal variability in simulated and observed tropical tropospheric temperature trends. Geophysical Research Letters, 44, 5709–5719. http://doi.org/10.1002/2017gl073798

65. Issued May 2017: Bechtel, B., Demuzere, M., Sismanidis, P., Fenner, D., Brousse, O., Beck, C., … Verdonck, M.-L. (2017). Quality of Crowdsourced Data on Urban Morphology—The Human Influence Experiment (HUMINEX). Urban Science, 1. http://doi.org/10.3390/urbansci1020015

66. Issued May 2017: Blender, R., & Badin, G. (2017). Construction of Hamiltonian and Nambu forms for the shallow water equations. Fluids, 2. http://doi.org/10.3390/fluids2020024

67. Issued May 2017: Droege, P., & Knieling, J. (Eds.). (2017a). Regenerative Räume: Leitbilder und Praktiken nachhaltiger Raumentwicklung. München: Oekom. https://www.oekom.de/nc/buecher/gesamtprogramm/buch/regenerative-raeume.html

68. Issued May 2017: Droege, P., & Knieling, J. (2017b). Regenerative Räume: Leitbilder und Praktiken nachhaltiger Raumentwicklung. In Regenerative Räume: Leitbilder und Praktiken nachhaltiger Raumentwicklung (pp. 1–17). München: Oekom. https://www.oekom.de/nc/buecher/gesamtprogramm/buch/regenerative-raeume.html

69. Issued May 2017: Goll, D. S., Winkler, A., Raddatz, T., Dong, N., Prentice, I. C., Ciais, P., & Brovkin, V. (2017). Carbon-nitrogen interactions in idealized simulations with JSBACH (version 3.10). Geoscientific Model Development, 10, 2009–2030. http://doi.org/10.5194/gmd-10-2009-2017

70. Issued May 2017: Graves, T., Franzke, C., Watkins, N. W., Gramacy, R. B., & Tindale, E. (2017). Systematic inference of the long-range dependence and heavy-tail distribution parameters of ARFIMA models. Physica A: Statistical Mechanics and Its Applications, 473, 60–71. http://doi.org/10.1016/j.physa.2017.01.028

71. Issued May 2017: Hasson, S., Lucarini, V. & Böhner, J. (2017): Prevailing climatic trends and runoff response from Hindukush-Karakoram-Hiamalaya, upper Indus basin. – Earth Syst. Dynam. 6: 579-653. doi:10.5194/esdd-6-579-2015.

72. Issued May 2017: Knieling, J., & Krekeler, M. (2017). Leitbilder als Instrument für eine nachhaltige Raumentwicklung,. In P. Droege & J. Knieling (Eds.), Regenerative Räume: Leitbilder und Praktiken nachhaltiger Raumentwicklung (pp. 21–32). München: Oekom. https://www.oekom.de/nc/buecher/gesamtprogramm/buch/regenerative-raeume.html

73. Issued May 2017: Li, Z., von Storch, J. S., & Müller , M. (2017). The K1 internal tide simulated by a 1/10° OGCM. Ocean Modelling, 113, 145–156. http://doi.org/10.1016/j.ocemod.2017.04.002

74. Issued May 2017: Tian, F., von Storch, J. S., & Hertwig, E. (2017). Air–sea fluxes in a climate model using hourly coupling between the atmospheric and the oceanic components. Climate Dynamics, 48, 2819–2836. http://doi.org/10.1007/s00382-016-3228-y

75. Issued May 2017: von Szombathely, M.; Albrecht, M.; Antanaskovic, D.; Augustin, J.; Augustin, M.; Bechtel, B.; Bürk, T.; Fischereit, J.; Grawe, D.; Hoffmann, P.; Kaveckis, G.; Krefis, A.C.; Oßenbrügge, J.; Scheffran, J.; Schlünzen, K.H. (2017) A Conceptual Modeling Approach to Health-Related Urban Well-Being. Urban Sci. 1, 17. http://www.mdpi.com/2413-8851/1/2/17

76. Issued April 2017: Arnds, D., Böhner, J. & Bechtel, B. (2017): Spatio-temporal variance and meteorological drivers of the urban heat island in a European city. – Theoretical and Applied Climatology 128 (1): 34-61. doi:10.1007/s00704-015-1687-4.

77. Issued April 2017: Brüggemann, M. (2017). Traditional and shifting roles of science journalists and environmental reporters covering climate change . Oxford Research Encyclopedia of Climate Science. http://doi.org/10.1093/acrefore/9780190228620.013.354

78. Issued April 2017: Müller, M., Oelmann, Y., Schickhoff, U., Böhner, J. & Scholten, T. (2017): Himalayan treeline soil and foliar C:N:P stoichiometry. – Geoderma 219: 21-32.
doi: 10.1016/j.geoderma.2016.12.015

79. Issued March 2017: Blender, R., & Badin, G. (2017). Viscous dissipation in 2D fluid dynamics as a symplectic process and its metriplectic representation. The European Physical Journal Plus, 132: 137. doi: 10.1140/epjp/i2017-11440-x.

80. Issued March 2017: Claussen, M., Dallmeyer, A., & Bader, J. (2017). Theory and modeling of the African humid period and the green Sahara . In Oxford Research Encyclopedia of Climate Science. http://doi.org/10.1093/acrefore/9780190228620.013.532

81. Issued March 2017: Rödder, S. (2017). The climate of science-art and the art-science of the climate: Meeting points, boundary objects and boundary work. Minerva, 55, 93–116. http://doi.org/10.1007/s11024-016-9312-y

82. Issued March 2017: Schmidt, J., Böhner, J., Brandl, R., & Opgenoorth, L. (2017): Mass elevation and lee effects markedly lift the elevational distribution of ground beetles in the Himalaya-Tibet orogen. – PLoS One 12 (3): e0172939. doi:10.1371/journal.pone.0172939.

83. Issued March 2017: Schubert-Frisius, M., Feser, F., von Storch, H., & Rast, S. (2017). Optimal spectral nudging for global dynamic downscaling. Monthly Weather Review, 145, 909–927. http://doi.org/10.1175/MWR-D-16-0036.1

84. Issued March 2017: Schwab, N., Schickhoff, U., Bürzle, B., Müller, M., Böhner, J., Chaudhary, R.P., Scholten, T. & Oldeland, J. (2017): Implications of tree species – environment relationships for the responsiveness of Himalayan krummholz treelines to climate change. – Journal of Mountain Science 14 (3): 453-473. doi: 10.1007/s11629-016-4257-z.

85. Issued March 2017: Tanski, G., Lantuit, H., Ruttor, S., Knoblauch, C., Radosavljevic, B., Strauss, J., Wolter, J., Irrgang, A. M., Ramage, J., & Fritz, M. (2017). Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic. Science of the Total Environment, 581, 434-447. doi: 10.1016/j.scitotenv.2016.12.152.

86. Issued March 2017 Tuia, D., Moser, G., Saux, B. L., Bechtel, B., & See, L. (2017). 2017 IEEE GRSS Data Fusion Contest: Open Data for Global Multimodal Land Use Classification [Technical Committees]. IEEE Geoscience and Remote Sensing Magazine, 5, 70–73. http://doi.org/10.1109/MGRS.2016.2645380

87. Issued March 2017: Yi, X., Hünicke, B., Tim, N., & Zorita, E. (2017). The relationship between Arabian Sea upwelling and Indian Monsoon revisited in a high resolution ocean simulation. Climate Dynamics. http://doi.org/10.1007/s00382-017-3599-8

88. Issued January 2017: Hense, I., Stemmler, I., & Sonntag, S. (2017). Ideas and perspectives: climate-relevant marine biologically driven mechanisms in Earth system models. Biogeosciences, 14(2), 403. https://doi.org/10.5194/bg-14-403-2017

89. Issued January 2017: Ehrmann, W., Schmiedl, G., Beuscher, S., & Krueger, S. (2017). Intensity of African Humid Periods Estimated from Saharan Dust Fluxes. PLoS One, 12: e0170989.
doi: 10.1371/journal.pone.0170989.

90. Issued December 2015: Hense, I., & Beckmann, A. (2015). A theoretical investigation of the diatom cell size reduction–restitution cycle. Ecological Modelling, 317, 66-82. https://doi.org/10.1016/j.ecolmodel.2015.09.003

91. Issued January 2017: Karki, R., Ul-Hasson, S., Schickhoff, U., Scholten, T. & Böhner, J. (2017): Rising Precipitation Extremes across Nepal. – Climate 5 (4), doi: 10.3390/cli5010004.

 

B Other publications

1.    Not dated: Mahmud, S. (n.d.). Communicating Climate Change: the Repertoire Approach. In 2nd World Symposium on Climate Change Communication. Graz, 07.-09.02.2018. Graz.

2.    Issued 2017: Scheffran, J. (Ed.). (2017b). Migration und Flucht zwischen Klimawandel und Konflikten, 9.

3.    Issued October 2017: Trümper, S. (2018). Nachhaltige Erinnerung im Journalismus: Konzept und Fallstudie zur Medienaufmerksamkeit für vergangene Flutkatastrophen (zugl.: Ph.-D Thesis 2016). PhD Thesis, Wiesbaden: Springer Fachmedien. http://doi.org/10.1007/978-3-658-19164-1

4.    Issued September 2017: Thomsen, S., Gröngröft, A., Reisdorff, C., Jensen, K., & Eschenbach, A. (2017). Einfluss von Bodenwasserverfügbarkeit und Mikroklima auf die Transpirationsdynamik von Stadtbäumen. Presented at the Jahrestagung der Deutschen Bodenkundlichen Gesellschaft, Göttingen.

5.    Issued September 2017: Titel, S., Gröngröft, A., & Eschenbach, A. (2017). Monitoring der Bodenwasserverfügbarkeit bei Straßenbaumstandorten in Hamburg. Presented at the Jahrestagung der Deutschen Bodenkundlichen Gesellschaft, Göttingen.

6.    Issued August 2017: Karabil, S. (2017). Mechanisms of sea level variability in the Baltic Sea region for the period 1850 - 2100 (PhD Thesis). Universität Hamburg, Hamburg. Retrieved from http://hdl.handle.net/11858/00-001M-0000-002D-DD9D-6

7.    Issued April 2017: Böhner, J., Dose, A., Held, H., & Scheffran, J. (Eds.). (2017). Energielandschaften Norddeutschland: Konferenz 2016 - Energiewende im Raum. Presented at the Energiewende im Raum, Hamburg: Centrum für Erdsystemforschung und Nachhaltigkeit (CEN) ; Cluster für erneuerbare Energien. Retrieved from http://hdl.handle.net/11858/00-001M-0000-002D-FFA7-F

8.    Issued April 2017: Braßler, M., v.d. Berk, I., & Holdschlag, A. (2017). Sustainable Futures: Studierende erstellen Open Educational Resources (OER) zum Thema Nachhaltigkeit. In K. Mayrberger (Ed.), HOOU Content Projekte der Vorprojektphase 2015/16 der Hamburg Open Online University. (pp. 50–53). Hamburg: Universität Hamburg. Retrieved from http://hdl.handle.net/11858/00-001M-0000-002D-D65B-0

9.    Issued April 2017: Held, H. (Ed.). (2017). Klimaökonomie: Kosteneffiziente Pfade zum 2-Grad-Ziel . In J. Scheffran, Energielandschaften Norddeutschland: Konferenz 2016 - Energiewende im Raum (pp. 8–9). Hamburg. Retrieved from http://hdl.handle.net/11858/00-001M-0000-002D-FFEE-4

10. Issued April 2017: Hoshyaripour, G. (2017). Volcanic ash particles hold clues to their history and effects. EOS, 98. http://doi.org/10.1029/2017EO070621

11. Issued April 2017: Link, M., & Shu, K. (2017). Energielandschaften:  Ost-China und Norddeutschland im Vergleich. In J. Böhner, A. Dose, & H. Held (Eds.), J. Scheffran, Energielandschaften Norddeutschland: Konferenz 2016 - Energiewende im Raum (pp. 16–17). Hamburg. Retrieved from http://hdl.handle.net/11858/00-001M-0000-002D-FFEC-8

12. Issued April 2017: Scheffran, J. (Ed.). (2017a). Geographische Vernetzungen in Energielandschaften: Stadt-Land-Energie . In J. Scheffran, Energielandschaften Norddeutschland: Konferenz 2016 - Energiewende im Raum (pp. 12–15). Hamburg. Retrieved from http://hdl.handle.net/11858/00-001M-0000-002D-FFEA-C

13. Issued March 2015: Schäfer, Mike S. (2015): Climate Change and the Media. In James Wright (Ed.): International Encyclopedia of the Social & Behavioral Sciences. Oxford: Elsevier, pp. 853–859. https://www.elsevier.com/books/international-encyclopedia-of-the-social-andampamp-behavioral-sciences/wright/978-0-08-097086-8

 

Date issued: 2017

Organisationstheoretische Perspektiven auf die Wissenschaftskommunikation

In der Diagnose, die moderne Gesellschaft sei eine ‚Gesellschaft von Organisationen‘ drückt sich die Bedeutung formaler Organisation für gesellschaftlich relevante Kommunikationsprozesse aus. Dies gilt auch für die Wissenschaftskommunikation: Das Wissenschaftsressort füllt die Wissensseite der Tageszeitung, Universitäten geben Pressemitteilungen heraus und Forscher und Forscherinnen werden in Medientrainings auf die Anforderungen medienöffentlicher Kommunikation vorbereitet. Dieser Beitrag befasst sich aus systemtheoretischer Perspektive mit den Grundlagen organisierter Wissenschaftsdarstellung und beschreibt und ordnet an ihr typischerweise beteiligte Organisationen. Argumentiert wird, dass die Relevanz von Organisationen für die Wissenschaftskommunikation am besten durch einen Vergleich dreier Organisationsformen herausgearbeitet werden kann, von denen die beiden ersten den Charakter eines Teilsystems einer Organisation haben, während der dritte eine eigene Organisation bildet: die Wissenschaftsredaktion einer Tageszeitung, die Pressestelle einer Forschungseinrichtung und der neue Organisationstyp des Science Media Centre. Anhand dieser Typologie lassen sich einige Funktionen und Folgen der Organisation von Wissenschaftskommunikation aufzeigen.

Read: Rödder, S. (2017). Organisationstheoretische Perspektiven auf die Wissenschaftskommunikation. In Bonfadelli, H., Fähnrich, B., Lüthje, C., Milde, J., Rhomberg, M., Schäfer, M.S. (Hrsg.),  Forschungsfeld Wissenschaftskommunikation (S. 63-81). Wiesbaden: Springer Fachmedien Wiesbaden.doi: 10.1007/978-3-658-12898-2_4, ISBN 978-3-658-12898-2.
Online:
https://www.springerprofessional.de/organisationstheoretische-perspektiven-auf-die-wissenschaftskomm/11002082 (Kapitel), http://www.springer.com/de/book/9783658128975 (Buch)
Contact: Simone Rödder (
simone.roedderdummy@uni-hamburgdummy2.de)

 

 

Date issued: 2017

Land use modelling as new approach for future hazard-sensitive population mapping in Northern Germany

Within this research, the authors are analyzing how the land use modeling can be used to map future hazard-sensitive population. The Greater Hamburg is presented as a case study area. The main idea of the research was model future environment, which could be used as a proxy to identify future hazard-sensitive populations. The study additionally presents the urban vulnerability climate zones' classification of the potential living areas in the Greater Hamburg  and how these zones can be related with historical population census data. The main result of the research is a future population mapping framework, which can be used as a guideline to model future hazard-sensitive population.

Read: Kaveckis, G., Bechtel, B., Pohl, T., & Ossenbrügge, J. (2017). Land use modelling as new approach for future hazard-sensitive population mapping in Northern Germany. In Awotona, A. (ed.), Planning for Community-based Disaster Resilience Worldwide: Learning from Case Studies in Six Continents. London and New York:  Routledge.
Online:
https://www.routledge.com/Planning-for-Community-based-Disaster-Resilience-Worldwide-Learning-from/Awotona/p/book/9781472468154
Contact:
Giedrius Kaveckis (giedriuskavdummy@gmaildummy2.com)

 

 

Date issued: 2 March 2017

Implications of tree species – environment relationships for the responsiveness of Himalayan krummholz treelines to climate change

In this paper, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths (3700-4200 m). We quantified species - environment relationships across the ecotone. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree species and thus constrain the future response of Himalayan krummholz treelines to climate warming.

Keywords: Himalaya, Nepal, Population structure, Rhododendron campanulatum, Spatial patterns, Species-environment relationships, Stand density, Variation partitioning
Read:
Schwab, N., Schickhoff, U., Bürzle, B., Müller, M., Böhner, J., Chaudhary, R. P., Scholten, T., & Oldeland (2017). Journal of Mountain Science, 14, 453-473. doi:10.1007/s11629-016-4257-z
Online:
http://link.springer.com/article/10.1007%2Fs11629-016-4257-z or http://rdcu.be/pHA9
Contact: Niels Schwab (niels.schwabdummy@uni-hamburgdummy2.de)

 

 

Date issued: February 2017

Sunk-cost fallacy and cognitive ability in individual decision-making

This paper reports on a laboratory experiment aiming at documenting the sunk-cost fallacy in individual decision-making and at identifying the role of the cognitive ability in its manifestation. For this purpose, the design rules out loss aversion and cognitive dissonance, identified by the literature as being the main psychological drivers of the bias. The sunk-cost fallacy is identified by comparing a low and a high sunk-cost treatment, respectively, against a control group that does not incur a sunk cost. There is evidence of a weak manifestation of the sunk-cost fallacy, which is statistically significant only for the high sunk-cost treatment. However, strong evidence of the fallacy was found among the high-cognitive-ability subjects. Finally, although cognitive ability is predictive of status-quo bias, it was not found to reduce the sunk-cost bias.
Keywords: Cognitive ability; Cognitive dissonance; Sunk-cost fallacy; Loss aversion
Read: Haita-Falah, C. (2016). Sunk-Cost Fallacy and Cognitive Ability in Individual Decision-Making. Journal of Economic Psychology, 58, 44-59. doi: 10.1016/j.joep.2016.12.001
Online:
http://www.sciencedirect.com/science/article/pii/S0167487016307346
Contact: Corina Haita-Falah (
haita-falahdummy@uni-kasseldummy2.de)

 

 

Date issued: 25 February 2017

Sea-ice thickness from field measurements in the northwestern Barents Sea

The Barents Sea is one of the fastest changing regions of the Arctic, and has experienced the strongest decline in winter-time sea-ice area in the Arctic, at math formula decade−1. Sea-ice thickness in the Barents Sea is not well studied. We present two previously unpublished helicopter-borne electromagnetic (HEM) ice thickness measurements from the northwestern Barents Sea acquired in March 2003 and 2014. The HEM data are compared to ice thickness calculated from ice draft measured by ULS deployed between 1994 and 1996. These data show that ice thickness varies greatly from year to year; influenced by the thermodynamic and dynamic processes that govern local formation vs long-range advection. In a year with a large inflow of sea-ice from the Arctic Basin, the Barents Sea ice cover is dominated by thick multiyear ice; as was the case in 2003 and 1995. In a year with an ice cover that was mainly grown in situ, the ice will be thin and mechanically unstable; as was the case in 2014. The HEM data allow us to explore the spatial and temporal variability in ice thickness. In 2003 the dominant ice class was more than 2 years old; and modal sea-ice thickness varied regionally from 0.6 to 1.4 m, with the thinner ice being either first-year ice, or multiyear ice which had come into contact with warm Atlantic water. In 2014 the ice cover was predominantly locally grown ice less than 1 month old (regional modes of 0.5–0.8 m). These two situations represent two extremes of a range of possible ice thickness distributions that can present very different conditions for shipping traffic; or have a different impact on heat transport from ocean to atmosphere.

Keywords: sea-ice; thickness measurements; Barents Sea
Read: King, J., Spreen, G., Gerland, S., Haas, C., Hendricks, S., Kaleschke, L., & Wang, C. (2017). Sea-ice thickness from field measurements in the northwestern Barents Sea. J. Geophys. Res. Oceans, 122. doi:10.1002/2016JC012199.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/2016JC012199/abstract
Contact: Lars Kaleschke (
lars.kaleschkedummy@uni-hamburgdummy2.de)

 

 

Date issued: 21 February 2017

Optimal Spectral Nudging for Global Dynamic Downscaling

This study analyzes a method of constructing a homogeneous, high-resolution global atmospheric hindcast. The method is the spectral nudging technique, which was applied to a state-of-the-art general circulation model (ECHAM6, T255L95). Large spatial scales of the global climate model prognostic variables were spectrally nudged toward a reanalysis dataset (NCEP-1, T62L28) for the past few decades. The main idea is the addition of dynamically consistent regional weather details to the coarse-grid NCEP-1 reanalysis. A large number of sensitivity experiments was performed, using different nudging e-folding times, vertical profiles, wavenumbers, and variables. Comparisons with observations and several reanalyses showed a high dependency on the variations of the nudging configuration. At the global scale, the accordance is very high for extratropical regions and lower in the tropics. A wavenumber truncation of 30, a relatively short e-folding time of 50 min, and a plateau-shaped nudging profile applied only to divergence and vorticity generally yielded the best results. This is one of the first global spectral nudging hindcast studies and the first applying an altitude-dependent profile to selected prognostic variables. The method can be applied to reconstructing the history of extreme events such as intense storms within the context of ongoing climate change.

Keywords: Hurricanes/typhoons; Regional effects; Spectral analysis/models/distribution; Climate models; General circulation models; Reanalysis data
Read:
Schubert-Frisius, M., Feser, F., von Storch, H., Rast, S. (2017). Optimal Spectral Nudging for Global Dynamic Downscaling. Monthly Weather Review, 145 (3).doi:10.1175/MWR-D-16-0036.1
Online:
http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-16-0036.1
Contact: Martina Schubert-Frisius( martina.schubert-frisiusdummy@hzgdummy2.de)

 

 

Date issued: 10 February 2017

Synoptic fluctuation of the Taiwan Warm Current in winter on the East China Sea shelf

The seasonal mean and synoptic fluctuation of the wintertime Taiwan Warm Current (TWC) were investigated using a well-validated finite volume community ocean model. The spatial distribution and dynamics of the synoptic fluctuation were highlighted. The seasonal mean of the wintertime TWC has two branches: an inshore branch between the 30 and 100 m isobaths and an offshore branch between the 100 and 200 m isobaths. The Coriolis term is much larger than the inertia term and is almost balanced by the pressure gradient term in both branches, indicating geostrophic balance of the mean current. Two areas with significant fluctuations of the TWC were identified during wintertime. One of the areas is located to the north of Taiwan with velocities varying in the cross-shore direction. These significant cross-shore fluctuations are driven by barotropic pressure gradients associated with the intrusion of the Taiwan Strait Current (TSC). When a strong TSC intrudes to the north of Taiwan, the isobaric slope tilts downward from south to north, leading to a cross-shore current from the coastal area to the offshore area. When the TSC intrusion is weak, the cross-shore current to the north of Taiwan is directed from offshore to inshore. The other area of significant fluctuation is located in the inshore area between the 30 and 100 m isobaths. The fluctuations are generally strong both in the alongshore and cross-shore directions, in particular at the latitudes 26.5 and 28° N. Wind affects the synoptic fluctuation through episodic events. When the northeasterly monsoon prevails, the southwestward Zhe-Min coastal current dominates the inshore area associated with a deepening of the mixed layer. When the winter monsoon is weakened or the southwesterly wind prevails, the northeastward TWC dominates in the inshore area.

Read: Xuan, J., Huang, D., Pohlmann, T., Su, J., Mayer, B., Ding, R., & Zhou, F. (2017). Synoptic fluctuation of the Taiwan Warm Current in winter on the East China Sea shelf. Ocean Sci., 13, 105-122. doi:10.5194/os-13-105-2017, 2017.
Online:
http://www.ocean-sci.net/13/105/2017/
Contact: Thomas Pohlmann (thomas.pohlmanndummy@uni-hamburgdummy2.de)

 

 

Date issued: 9 February 2017

Biome changes in Asia since the mid-Holocene – an analysis of different transient Earth system model simulations

The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate–vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere–ocean(–vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions.
Read:
Dallmeyer, A., Claussen, M., Ni, J., Cao, X., Wang, Y., Fischer , N., Pfeiffer, M., Jin , L., Khon, V., Wagner, S., Haberkorn, K. & Herzschuh, U. (2017). Holocene biome changes in Asia - an analysis of different transient Earth system model simulations. Climate of the Past, 13, 107-134. doi:10.5194/cp-13-107-2017
More:
http://www.clim-past.net/13/107/2017/
Contact: Martin Claussen (
martin.claussendummy@mpimet.mpgdummy2.de)

 

 

Date issued: 3 February 2017

Depth-averaged non-hydrostatic extension for shallow water equations with quadratic vertical pressure profile: equivalence to Boussinesq-type equations

For the mathematical description of dispersive long wave gravity waves, there are two different analytical approaches and types of resulting equation sets, namely the Boussinesq-type equations and the non-hydrostatic extension. We show that only one assumption in the depth- averaged non-hydrostatic extension has to be changed to get equivalent systems of equations for both approaches. This assumption is the vertical profile of the non-hydrostatic pressure.
Keywords: hallow water; non-hydrostatic pressure; Boussinesq-type equations; Serre equations; free surface; pressure profile; Green–Nagdhi equations
Read: Jeschke, A., Pedersen, G. K., Vater, S., & Behrens, J. (2017). Depth-averaged non-hydrostatic extension for shallow water equations with quadratic vertical pressure profile: equivalence to Boussinesq-type equations. Int. J. Numer. Meth. Fluids. doi: 10.1002/fld.4361.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/fld.4361/abstract;jsessionid=4FDD1D4F6381D5D775397C5F37443504.f02t02
Contact: Anja Jeschke (
anja.jeschkedummy@uni-hamburgdummy2.de)

 

 

Date issued: January 2017

Testing the Quality of Sea-Level Data Using the GECCO Adjoint Assimilation Approach

Besides providing an estimate of the changing ocean state, an important result of the dynamically consistent estimating the circulation and climate of the ocean (ECCO) state estimate approach is the provision of a posterior model–data residuals which contain important information about elements in the assimilated observations that are inconsistent with the model dynamics or with the information present in other ocean data sets that are being used as constraints in the assimilation procedure. Based on decreased GECCO2 model–data residuals, upon using the altimeter data through the ESA climate change initiative (cci) sea-level (SL) project, we show here that the recently reprocessed ESA SL_cci altimeter data set (SL1) has been improved relative to the earlier AVISO altimetry data set and is now more consistent with the GECCO2 estimate and with the information about the changing ocean state embedded in other ocean data sets. The improvement can be shown to exist separately for both TOPEX/POSEIDON and ERS data sets. The study reveals that especially in regions characterized by small sea surface height (SSH) variability and small signal-to-noise ratio in the SSH data, improvements can be on the order of 30% of previously existing model–data residuals. However, in some regions we can find degradations, particulary in those where GECCO2 has little skill in representing the altimeter data and where evaluation of the products with GECCO2 is thus not advisable. Upon the assimilation of the new SL1 data set, the GECCO2 synthesis was further improved. However, adding the sea surface temperature (SST) from the SST_cci project as additional constrain, no further impact can be identified.

Keywords: Altimeter observations, Data assimilation, Ocean state estimate, Ocean Modelin, GECCO: German partner of the Estimating the Circulation and Climate of the Ocean effort
Read:
Scharffenberg, M.G., Köhl, A. & Stammer, D. (2017). Testing the Quality of Sea-Level Data Using the GECCO Adjoint Assimilation Approach. Surv Geophys,  38 (1), 349-383. doi:10.1007/s10712-016-9401-3
Online:
http://link.springer.com/article/10.1007/s10712-016-9401-3?wt_mc=Internal.Event.1.SEM.ArticleAuthorAssignedToIssue#enumeration
Contact: Martin Scharffenberg (
martin.scharffenbergdummy@uni-hamburgdummy2.de)

 

 

Date issued: 24 January 2017

Process-based modelling of the methane balance in periglacial landscapes (JSBACH-methane) - Model description paper

A detailed process-based methane module for a global land surface scheme has been developed which is general enough to be applied in permafrost regions as well as wetlands outside permafrost areas. Methane production, oxidation and transport by ebullition, diffusion and plants are represented. In this model, oxygen has been explicitly incorporated into diffusion, transport by plants and two oxidation processes, of which one uses soil oxygen, while the other uses oxygen that is available via roots. Permafrost and wetland soils show special behaviour, such as variable soil pore space due to freezing and thawing or water table depths due to changing soil water content. This has been integrated directly into the methane-related processes. A detailed application at the Samoylov polygonal tundra site, Lena River Delta, Russia, is used for evaluation purposes. The application at Samoylov also shows differences in the importance of the several transport processes and in the methane dynamics under varying soil moisture, ice and temperature conditions during different seasons and on different microsites. These microsites are the elevated moist polygonal rim and the depressed wet polygonal centre. The evaluation shows sufficiently good agreement with field observations despite the fact that the module has not been specifically calibrated to these data. This methane module is designed such that the advanced land surface scheme is able to model recent and future methane fluxes from periglacial landscapes across scales. In addition, the methane contribution to carbon cycle–climate feedback mechanisms can be quantified when running coupled to an atmospheric model.

Read: Kaiser, S., Göckede, M., Castro-Morales, K., Knoblauch, C., Ekici, A., Kleinen, T., Zubrzycki, S., Sachs, T., Wille, C., & Beer, C. (2017). Process-based modelling of the methane balance in periglacial landscapes (JSBACH-methane). Geosci. Model Dev., 10, 333-358. doi:10.5194/gmd-10-333-2017
Online:
http://www.geosci-model-dev.net/10/333/2017/
Contact: Sebastian Zubrzycki (
Sebastian.Zubrzyckidummy@uni-hamburgdummy2.de)

 

 

Date issued: 22 January 2017

REDD+: Quick Assessment of Deforestation Risk Based on Available Data

We carried out a study to provide a new modeling approach able to identify areas that are prone to near-future deforestation. The evaluation of the future dynamics of deforestation is often a challenging task, especially for countries that have to cope with a critical lack of data and capacities. To support developing countries in assessing locations of deforestation risk, we developed a straightforward approach that integrates a machine learning technique (such as Random Forest), available geo-spatial layers, and easily accessible data sources.

Keywords: REDD+; tropical forests; spatial targeting; random forests; carbon; land-use change modelling
Read: Di Lallo, G., Mundhenk, P., Zamora López, S. E., Marchetti, M., & Köhl, M. (2017). REDD+: Quick Assessment of Deforestation Risk Based on Available Data. Forests, 8 (1), 29. doi:10.3390/f8010029
Online:
http://www.mdpi.com/1999-4907/8/1/29
Contact: Giulio Di Lallo (
giulio.di.lallodummy@uni-hamburgdummy2.de)

 

 

Date issued: 18 January 2017

Models, manifestation and attribution of climate change

Results from a series of five surveys among five groups of international climate scientists about  their evaluation of elements of climate models and of climate change are presented. The first survey was done in 1996, the latest in 2015/16. Thus, our snapshots of the opinions of climate scientists cover 20 years. The results describe a strong increase in agreement concerning issues of manifestation of climate change, i.e., that the warming is real and not influenced bychanging measuring and reporting practices, and concerning attribution of this ongoing climate change to ongoing anthropogenic causes. On the other hand, the evaluation of the climate models has changed little in the past 20 years. There are still significant reservations with the models ability to incorporate clouds and to describe rainfall.

Obviously the growing conviction of ongoing man-made climate change is based on a variety of explanations, with modelling not being the predominant line of evidence. We suggest that it may be the repeated assessments by the IPCC, based on paleoclimatic evidence and stringent statistical analysis of the instrumental record which have led to the growing consensus of the warming and its causation.

We stress that the presented results concern the opinion of climate scientists with a rather broad background. Our results do not assess if the opinions of the surveyed scientists are “valid” or “right”, but they recognize the character of science being a social process.

Keywords:
survey, climate change, models, climate scientists
Read: von Storch, H., Bray, D. G.
(2017). Models, manifestation and attribution of climate change. Meteorol. Hydrol. Water Manag., 5 (1), 47-52.
Online: http://www.mhwm.pl/Models-manifestation-and-attribution-of-climate-change,0,53.html
Contact: Hans von Storch (
hans.von.storchdummy@hzgdummy2.de)

 

 

Date issued: 18 January 2017 (in press)

Toward downscaling oceanic hydrodynamics – suitability of a high-resolution OGCM for describing regional ocean variability in the South China Sea

We suggest to transfer the empirical downscaling methodology, which was developed mostly for atmospheric dynamics and impacts, to regional ocean problems. The major problem for doing so is the availability of decades-long and homogeneous and spatially detailed data sets. We have examined the performance of the STORM multidecadal simulation, which was run on a 0.1° grid and forced with 1950–2010 NCEP re-analyses, in the South China Sea and found the data suitable. For demonstration we build with this STORM-data downscaling model for the regional throughflow.

The STORM data is compared with AVISO satellite observations and the ocean re-analysis dataset C-GLORS. We find the seasonal patterns and the inter-annual variability of sea surface height anomaly in both the C-GLORS data and the STORM simulation consistent with the AVISO-satellite data. Also the strong westward intensification and the seasonal patterns of South China Sea circulation steered by the monsoon have been presented well. As an important indicator of vertical movement, the sea surface temperature distribution maps are also very close, especially for the narrow upwelling region in summer. We conclude that the output of the STORM simulation is realistically capturing both the large-scale as well as the small-scale dynamical features in the South China Sea.

Keywords: Ocean downscaling; STORM; The South China Sea
Read: 张萌 (Zhang M.), & von Storch, H. (2017, in press). Towards downscaling oceanic hydrodynamics - Suitability of a high-resolution OGCM for describing regional ocean variability in the South China Sea. Oceanologia, 59 (2), 166–176. doi:http://dx.doi.org/10.1016/j.oceano.2017.01.001
Online: http://www.sciencedirect.com/science/article/pii/S0078323417300027
Contact: Hans von Storch (
hans.von.storchdummy@hzgdummy2.de)

 

 

Date issued: 13 January 2017

Rising Precipitation Extremes across Nepal

This paper highlights the prevailing trends of precipitation mean and extremes across Nepal. The result indicates a prolongation of dry periods and a decrease in post-monsoon precipitation across the whole country, while annual and high-intensity precipitation extremes show contrasting evidence of increase in the western half and a moderately decreasing pattern in the east. Similarly, winter precipitation has significantly decreased across the western region, thereby indicating the weakened influence of western disturbances.

Keywords: Nepal; spatial precipitation pattern; precipitation extremes; consecutive dry days; high-intensity precipitation
Read
: Karki, R., ul Hasson, S., Schickhoff, U., Scholten, T., & Böhner (2017). J. Rising Precipitation Extremes across Nepal. Climate. 5 (1), 4, doi:10.3390/cli5010004.
Online:
http://www.mdpi.com/2225-1154/5/1/4
Contact: Ramchandra Karki (
Ramchandra.Karkidummy@studium.uni-hamburgdummy2.de)

 

 

Date issued: 6 January 2017

Extremes in dynamic-stochastic systems

Extreme events capture the attention and imagination of the general public. Extreme events,especially meteorological and climatological extremes, cause significant economic damages and lead to a significant number of casualties each year. Thus, the prediction of extremes is  of obvious importance. Here, I will survey the predictive skill and the predictability of extremes using dynamic-stochastic models. These dynamic-stochastic models combine deterministic nonlinear dynamics with a stochastic component, which consists potentially of both additive and multiplicative noise components. In these models, extremes are created by either the nonlinear dynamics, multiplicative noise, or additive heavy-tailed noises. These models naturally capture the observed clustering of extremes and can be used for the prediction of extremes.

Keywords: Extreme events, stochastic processes, time series analysis, cluster analysis, computer modeling
Read: Franzke, C. L. E. (2017). Extremes in dynamic-stochastic systems. Chaos 27 (1), 012101. doi:10.1063/1.4973541
More:
http://aip.scitation.org/doi/abs/10.1063/1.4973541
Contact: Christian Franzke (
christian.franzkedummy@uni-hamburgdummy2.de)

 

 

Date issued: 3 January 2017

Himalayan treeline soil and foliar C:N:P stoichiometry indicate nutrient shortage with elevation

Only a few studies have addressed the soil and foliar carbon:nitrogen:phosphorus (C:N:P) stoichiometry in alpine treeline ecotones. Moreover, information on the soil nutrient availability (primarily N, P) in such ecosystems is rare. To fill these gaps, we performed a multiple data sampling in a near-natural alpine treeline ecotone in Rolwaling Himal, Nepal.

Our results show strongly varying soil C:N:P ratios and nutrient availability with soil depth. Caused by high monsoon precipitation and coarse-grained soils with low water-holding capacities, a vertical transport of nutrients and potentially mineralizable soil organic matter (SOM) in soils occurs, which is a general problem in the study area impeding growing conditions for trees. Soil N and P availability, and soil C:P and N:P ratios decrease significantly as elevation increases, especially at the transition from krummholz (dominated by Rhododendron campanulatum) to the alpine tundra (dwarf scrub heath). Soil C:N ratios increase significantly with elevation, most notably from the subalpine forest to krummholz and the alpine tundra. These altitudinal trends indicate increasing nutrient (N, P) shortage especially in the alpine tundra. Low N and P availability in alpine tundra soils are likely caused by a lower litter input from dwarf shrub vegetation, and a decline in litter mineralization in this altitudinal zone resulting in small accumulation of SOM. Nutrient availability in the entire study area is generally limited by low soil pH (from 2.5 to 4). In total six investigated tree species show diverse relationships between foliar and soil stoichiometric ratios, and soil nutrient availability. Significantly increasing foliar C:N and C:P ratios with elevation due to significantly decreasing foliar N and P concentrations suggest a limitation in N and P. Foliar N:P ratios indicate N rather than P limitation. Contrary to previous studies from different alpine treeline ecotones, we do not consider the Rolwaling treeline ecotone as an area of nutrient accumulation. We conclude that altitudinal variations in stand structures themselves govern nutrient cycling through the input of C, N, and P into soils by differences in leaf fall.

Keywords: Carbon; C:N:P stoichiometry; Nitrogen; Phosphorus; Soil; Treeline
Read
: Müller, M., Oelmann, Y., Schickhoff, U., Böhner, J., & Scholten, S. (2017). Himalayan treeline soil and foliar C:N:P stoichiometry indicate nutrient shortage with elevation.
Geoderma 291 (1), 21-32. doi:http://dx.doi.org/10.1016/j.geoderma.2016.12.015.
Online:
http://www.sciencedirect.com/science/article/pii/S0016706116310357
Contact: Jürgen Böhner (
juergen.boehnerdummy@uni-hamburgdummy2.de)

 

 

Date issued: 2016

Integrated Water Resources Management in Brazil: Participatory
Approaches as a Way to Resource Justice?

The article uses Nancy Frasers concept of social justice – including the notions of redistribution, recognition and representation – to analyse participation mechanisms in the water sector. Since the Conference on Water and Environment in 1992, an Integrated Water Resources Management can be seen as the new paradigm for water governance, claiming participation mechanisms as the main instrument for a more just redistribution of water. By analysing the framing of this new management approach within the discourses of water resources and scarcity and by using empirical experiences from the state of Ceará (Brazil), the article questions the relation between participation and social justice.

Keywords: Natural resources Political aspects, environmental policy, environmental justice
Read
: Schmitt, T. (2016).
Integrated Water Resources Management in Brazil: Participatory
Approaches as a Way to Resource Justice? In: Pichler, M., Staritz, C., Küblböck, K., Plank, C., Raza, W., & Ruiz Peyré, F. (Hrsg.), Fairness and Justice in Natural Resource Politics (S.73‐89). London und New York:  Routledge.

Online:
https://beluga.sub.uni-hamburg.de/vufind/Record/856272175?rank=1
Contact: Tobias Schmitt (
tobias.schmittdummy@uni-hamburgdummy2.de)

 

 

Date issued: December 2016

Increasing social welfare by taxing pesticide externalities in the Indian cotton sector

External pesticide costs in India's cotton production can be internalised partially without substantially affecting consumer surplus while still increasing social welfare, but producers need to have access to and the knowledge to employ all available cotton production technologies to minimise losses.

Keywords: Bt cotton; farmer field schools; IPM; Pigovian tax
Read
: Rasche, L., Dietl, A., Shakhramanyan, N. G., Pandey, D., Schneider, U. A. (2016). Increasing social welfare by taxing pesticide externalities in the Indian cotton sector. Pest Management Science. doi:10.1002/ps.4275.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/ps.4275/full
Contact: Livia Rasche (
livia.raschedummy@uni-hamburgdummy2.de)

 

 

Date issued: 30 December 2016 (accepted)

Ecological relevance of salps and doliolids in the northern Benguela Upwelling System

Thaliacea are effective pelagic filter-feeders able to spawn in massive blooms, thereby grazing large amounts of phytoplankton and microzooplankton. Sinking faecal pellets as well as dead and moribund animals provide an enhanced carbon flux into deeper layers. Large Thaliacea blooms were detected during moderate upwelling conditions in the northern Benguela Current Region. First estimates revealed that 25 – 100 % of the daily primary production was consumed during blooms.

Keywords: Thaliacea, carbon flux, upwelling, Namibia, Benguela
Read
:
Martin, B., Koppelmann, R., & Kassatov, P. (2016, accepted). Ecological relevance of salps and doliolids in the northern Benguela Upwelling System. J Plankton Res 1-15.  doi:10.1093/plankt/fbw095.
Online:
https://academic.oup.com/plankt/article/2758648/Ecological-relevance-of-salps-and-doliolids-in-the 
Contact: Rolf Koppelmann (
rolf.koppelmanndummy@uni-hamburgdummy2.de)

 

 

Date issued: 20 December 2016

Effects of Oil Sanctions on Iran’s Economy and Household Welfare: New Evidence from A CGE Model

This chapter treats the economic and welfare consequences of Western-backed oil-export sanctions against Iran. Oil sanctions were imposed on post-revolutionary Iran with the supposed goal of changing its government’s political behavior. We aim to answer the following questions: (a) What were the likely effects of oil sanctions on the Iranian macroeconomic variables? (b) What were the likely effects of oil sanctions on Iran’s household welfare?

Read: Farzanegan , M. R., Khabbazan, M. M., Sadeghi, H. (2016). Effects of Oil Sanctions on Iran’s Economy and Household Welfare: New Evidence from A CGE Model (pp 185-211). In Farzanegan, Mohammad Reza, Alaedini, Pooya (Eds), Economic Welfare and Inequality in Iran – Developments since the Revolution, Palgrave Macmillan US. doi:10.1057/978-1-349-95025-6_8
Online: http://link.springer.com/chapter/10.1057/978-1-349-95025-6_8
Contact: Mohammad Mohammadi Khabbazan (
mohammad.mohammadidummy@uni-hamburgdummy2.de)

 

 

Date issued: 20 December 2016

Household Welfare in Iran Under Banking Sanctions: From Open Economy Toward Autarchy

Over the last three decades, the role of economic sanctions in foreign policy has rapidly expanded (Institute for International Economics 2002). Economic sanctions are non-military measures that aim to change a target state’s behavior (Kaempfer and Lowenberg 2007). Some analysts argue that economic sanctions are incapable of achieving their goals, because they have no real influence on the target economy’s rulers (Drezner 1999; Elliott 1998; Hufbauer et al. 1990; Pape 1997). Others suggest that whereas sanctions may have a relatively high chance of success in the immediate period after their implementation (Dizaji and van Bergeijk 2013), over time, the target economy is likely to adjust to the imposed constraints by reallocating its resources (see Chap. 8; Dizaji and van Bergeijk 2013; Siddig 2011).

Read: Khabbazan, M. M., Farzanega, M. R. (2016). Household Welfare in Iran Under Banking Sanctions: From Open Economy Toward Autarchy (pp 213-232). In Farzanegan, Mohammad Reza, Alaedini, Pooya (Eds), Economic Welfare and Inequality in Iran – Developments since the Revolution, Palgrave Macmillan US. doi: 10.1057/978-1-349-95025-6_9
Online:
http://link.springer.com/chapter/10.1057/978-1-349-95025-6_9
Contact: Mohammad Mohammadi Khabbazan (
mohammad.mohammadidummy@uni-hamburgdummy2.de)

 

 

Date issued: 8 November 2016

Post-eruptive flooding of Santorini caldera and implications for tsunami generation

Caldera-forming eruptions of island volcanoes generate tsunamis by the interaction of different eruptive phenomena with the sea. Such tsunamis are a major hazard, but forward models of their impacts are limited by poor understanding of source mechanisms. The caldera-forming eruption of Santorini in the Late Bronze Age is known to have been tsunamigenic, and caldera collapse has been proposed as a mechanism. Here, new bathymetric and seismic evidence shows that the caldera was not open to the sea during the main phase of the eruption, but was flooded once the eruption had finished. Inflow of water and associated landsliding cut a deep, 2.0-2.5 km3 submarine channel, filling the caldera in less than a couple of days. If, as at most such volcanoes, caldera collapse occurred syneruptively, then it cannot have generated tsunamis. Entry of pyroclastic flows into the sea, combined with slumping of submarine pyroclastic accumulations, were the main mechanisms of tsunami production.

Keywords:    Natural hazards, Volcanology
Read: Nomikou, P., Druitt, T.H., Hübscher, C., Mather, T.A., Paulatto, M., Kalnins, L.M., Kelfoun, K., Papanikolaou, D., Bejelou, K., Lampridou, D., Pyle, D.M., Carey, S., Watts, A.B., Weiß, B., & Parks, M.M. (2016). Post-eruptive flooding of Santorini caldera and implications for tsunami generation. Nature Communications 7. doi:10.1038/ncomms13332.
Online: http://www.nature.com/articles/ncomms13332
Contact: Christian Hübscher (
christian.huebscherdummy@uni-hamburgdummy2.de)

 

 

Date issued: 18 November 2016

Benefits of Coordinated Water Resource System Planning in the Cauca-Magdalena River Basin

A coordinated planning of investments in water management infrastructures increases welfare by 2–18% over the next century in the Magdalena river basin in Colombia, which corresponds to average annual savings from US$ 610 million to US$ 6.4 billion. Benefits increase as water availability decreases. Results also show that water demand from the agricultural sector is projected to rise in future, which further underlines the necessity for robust governance mechanisms to keep conflicts between sectors to a minimum.

Keywords: Colombia; capacity expansion; dynamic optimization; investment decisions; water infrastructures
Read: Rasche, L., Schneider, U. A., Bolivar Lobato, M., Sos Del Diego, R. & Stacke, T. (2016). Benefits of coordinated water resource system planning in the Cauca-Magdalena river basin. Water Economics and Policy. doi:http://dx.doi.org/10.1142/S2382624X1650034X.
Online: http://www.worldscientific.com/doi/abs/10.1142/S2382624X1650034X
Contact: Livia Rasche (
livia.raschedummy@uni-hamburgdummy2.de)

 

 

Date issued: 17 October 2016

Immer Ärger mit der Materialität? – Politische Ökologie und das Dispositiv der Dürre im Nordosten Brasiliens

While the role of materiality was understudied in most social sciences, there was a sensibility for these issues in political ecology. [...] Following the considerations of Michel Foucault, this article explores whether dispositive analysis as a concept and as a method offers a way to integrate both social and material conditions into studies of political ecology. By examining water infrastructure and the dispositive of drought in Northeastern Brazil, this paper displays how dispositive analysis is a means to identify different elements, their autonomies as well as their interconnectedness. Focusing on the entanglements of discourses, institutionalizations, subjectivity, practices and materiality allows capturing the materiality of discourses and the discursivity of material orders.

Read: Schmitt, T. (2016). Immer Ärger mit der Materialität? – Politische Ökologie und das Dispositiv der Dürre im Nordosten Brasiliens. Geogr. Helv., 71, 229-244. doi:10.5194/gh-71-229-2016, 2016.
Online: http://www.geogr-helv.net/71/229/2016/
Contact: Tobias Schmitt (tobias.schmittdummy@uni-hamburgdummy2.de)

Date issued: 13 July 2016

Sea ice leads in the Arctic Ocean: Model assessment, interannual variability and trends

Scientists from the Alfred-Wegener-Institute (AWI) and the University of Hamburg have succeeded in realistically simulating the emergence of large channels in the Artic sea ice in a computer model. Two approaches were decisive for this success: On the one hand, the researchers had increased the spatial resolution of the FESOM AWI sea-ice ocean model. On the other hand, they were able to improve the numerical solution to the equation so that the simulation of the lead formation holds up well when compared to real sea-ice satellite data.

Read: Wang, Q., Danilov, S., Jung, T., Kaleschke, L., & Wernecke, A. (2016). Sea ice leads in the Arctic Ocean: Model assessment, interannual variability and trends. Geophysical Research Letters, 43(13), 7019-7027.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/2016GL068696/abstract;jsessionid=470F7333E5F66AC686F730F0206D47E4.f02t03

 

Date issued: 13 July 2016

Nonlinear stratospheric variability: multifractal de-trended fluctuation analysis and singularity spectra

Characterizing the stratosphere as a turbulent system, temporal fluctuations often show different correlations for different time scales as well as intermittent behaviour that cannot be captured by a single scaling exponent. In this study, the different scaling laws in the long-term stratospheric variability are studied using multifractal de-trended fluctuation analysis (MF-DFA). The analysis is performed comparing four re-analysis products and different realizations of an idealized numerical model, isolating the role of topographic forcing and seasonal variability, as well as the absence of climate teleconnections and small-scale forcing. The Northern Hemisphere (NH) shows a transition of scaling exponents for time scales shorter than about 1 year, for which the variability is multifractal and scales in time with a power law corresponding to a red spectrum, to longer time scales, for which the variability is monofractal and scales in time with a power law corresponding to white noise. Southern Hemisphere (SH) variability also shows a transition at annual scales. The SH also shows a narrower dynamical range in multifractality than the NH, as seen in the generalized Hurst exponent and in the singularity spectra. The numerical integrations show that the models are able to reproduce the low-frequency variability but are not able to fully capture the shorter term variability of the stratosphere.

Read: Badin, G., & Domeisen, D. I. (2015). Nonlinear stratospheric variability: multifractal detrended fluctuation analysis and singularity spectra. arXiv preprint arXiv:1511.00810. DOI: 10.1098/rspa.2015.0864.
Online: http://rspa.royalsocietypublishing.org/content/472/2191/20150864

Contact: Gualtiero Badin (gualtiero.badindummy@uni-hamburgdummy2.de)

 

Date issued: 11 July 2016

Changes in summer sea ice, albedo, and portioning of surface solar radiation in the Pacific sector of Arctic Ocean during 1982-2009

Satellite data were used to estimate Arctic sea ice albedo, long-term trends and seasonal evolutions. A distinct change in the seasonal evolution of ice albedo at the SHEBA geolocations has occurred since 2007. Summer evolution of ice albedo matched ice surface melting and  ponding well at basin scale. A positive Arctic Dipole Anomaly might enhance the ice-albedo feedback in the  Pacific sector of Arctic Ocean.

Read: Lei, R., Tian‐Kunze, X., Leppäranta, M., Wang, J., Kaleschke, L., & Zhang, Z. (2016). Changes in summer sea ice, albedo, and portioning of surface solar radiation in the Pacific sector of Arctic Ocean during 1982‐2009. Journal of Geophysical Research: Oceans.
Online: http://onlinelibrary.wiley.com/doi/10.1002/2016JC011831/full

Contact: Lars Kaleschke (lars.kaleschkedummy@uni-hamburgdummy2.de)

 

Date issued: 07 July 2016

WUDAPT, an efficient land use producing data tool for mesoscale models? Integration of urban LCZ in WRF over Madrid

The absence of suitable data that describes the urban landscape in climate relevant terms for climatic models is a significant impediment to progress. To address this data gap the World Urban Database and Access Portal Tools (WUDAPT) project focuses on creating a global database on cities suited for urban climate studies. In this paper, the potential of WUDAPT level 0 data for use in the application of the Weather Research Forecasting (WRF) model with the Building Effect Parameterization and Building Energy Model (BEP-BEM) scheme was tested for Madrid (Spain) during winter and summer.  The results show that the data scheme improves model performance comparable to CORINE land-cover data.

Read: Brousse, O., Martilli, A., Foley, M., Mills, G., & Bechtel, B. (2016). WUDAPT, an efficient land use producing data tool for mesoscale models? Integration of urban LCZ in WRF over Madrid. Urban Climate, 17, 116-134.
Online: http://www.sciencedirect.com/science/article/pii/S2212095516300219

Contact: Benjamin Bechtel (benjamin.bechteldummy@uni-hamburgdummy2.de)

 

Date issued: 06 July 2016

Corporate investments and environmental regulation: The role of regulatory uncertainty, regulation-induced uncertainty, and investment history

The relation between uncertainty related to environmental regulation and corporate investments has received considerable attention in the academic literature. Previous quantitative studies, however, have not distinguished between different types of perceived regulation-related uncertainty and do not consider the potential influence of prior investments on firms' investment decisions. Therefore, this paper analyzes how decision makers' perception of two types of uncertainties – regulatory and regulation-induced uncertainty – affects corporate investments in measures to reduce environmental impact. We analyze survey data from a sample of more than 250 companies participating in the EU Emissions Trading System. The data set includes firms from different industries and countries, and covers the first two periods of the trading scheme. Regression results reveal that regulation-induced uncertainty is positively related to a firm's decision to invest, while we find no statistically significant relation to regulatory uncertainty. Moreover, we find that investment history is positively associated with investments in a specific year, but does not moderate the uncertainty–investment relation.

Read: Lopez, J. M. R., Sakhel, A., & Busch, T. (2016). Corporate investments and environmental regulation: The role of regulatory uncertainty, regulation-induced uncertainty, and investment history. European Management Journal.
Online: http://www.sciencedirect.com/science/article/pii/S0263237316300627

Contact: Juan Miguel Rodriguez Lopez (miguel.rodriguezdummy@uni-hamburgdummy2.de)

 

Date issued: 04 July 2016

North Atlantic summer storm tracks over Europe dominated by internal variability over the past millennium

Certain large, sustained anomalies in European temperatures in the past millennium are probably the result of internal variation. Such internal variations can modulate regional temperatures away from the expected response to greenhouse gas forcing. Here we assess the causes of European summer temperature variability over the past millennium using temperature observations, simulations and reconstructions. We find multidecadal-mean summer temperatures have varied within a span of 1 K, largely controlled by external forcing. By contrast, we find subcontinental variations, described by the temperature contrast between northern and southern Europe (the meridional temperature gradient), vary with a span of 2 K, and are controlled by internal processes. These variations are the result of redistributions of precipitation and cloud cover linked to oscillations in the position of the summer storm track. In contrast to recent twentieth-century winter-time trends, variations of the summer storm track over the past millennium show a weak response to external forcing, and instead are dominated by stochastic internal variability. We argue that the response of European summer temperatures to anthropogenic greenhouse forcing is likely to be spatially modulated by the same stochastic internal processes that have caused periods of cool, wet summers in northern Europe over the last millennium.

Read: Gagen, M. H., Zorita, E., McCarroll, D., Zahn, M., Young, G. H., & Robertson, I. (2016). North Atlantic summer storm tracks over Europe dominated by internal variability over the past millennium. Nature Geoscience.
Online: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2752.html

Contact: Eduardo Zorita (eduardo.zoritadummy@hzgdummy2.de)

 

Date issued: 24 June 2016

Antarctic sea-ice thickness retrieval from ICESat: Inter-comparison of different approaches

Laser altimetry from satellite is one possibility to derive the thickness of sea ice floating on the Southern Ocean around Antarctica. One of the main prerequisites for reliable retrieval of the sea-ice thickness is accurate knowledge of the snow depth on the sea ice. This has been and will be a challenge. The present paper reports on an inter-comparison of various sea-ice thickness retrieval approaches which differ in their way how snow depth is treated. Thereby the paper contributes to our knowledge about the uncertainty of Antarctic sea-ice thickness retrieved from satellite laser altimetry. Two data sets associated with this paper are available under http://icdc.zmaw.de/projekte/esa-cci-sea-ice-ecv0.html.

Read: Kern, S., Ozsoy-Çiçek, B., & Worby, A. P. (2016). Antarctic Sea-Ice Thickness Retrieval from ICESat: Inter-Comparison of Different Approaches. Remote Sensing, 8(7), 538.
Online: http://www.mdpi.com/2072-4292/8/7/538

 

Date issued: 21 June 2016

The impact of gradient wind imbalance on tropical cyclone intensification within Ooyama’s three-layer model

This paper addresses the validity of the gradient wind balance approximation during the intensification phase of a tropical cyclone in Ooyama’s three-layer model. For this purpose the sensitivity to various model modifications is examined which are given by the inclusion of i) unbalanced dynamics in the free-atmosphere, ii) unbalanced dynamics in the slab-boundary layer, iii) a height-parameterized boundary layer model and iv) a rigid lid. The most rapid intensification occurs when the model employs the unbalanced slab-boundary layer while the simulation with the balanced boundary layer revealed the slowest intensification. The simulation with the realistic height-parameterized boundary layer model exhibits an intensification rate that lies in between. Intensification was induced by a convective ring in all experiments but a distinct contraction of the radius of maximum gradient wind only takes place with unbalanced boundary layer dynamics. In all experiments the rigid lid and the balance approximation for the free-atmosphere have no crucial impact on intensification and a linear stability analysis cannot explain the found sensitivity to intensification. Most likely, the nonlinear momentum advection term plays an important role in the boundary layer. It is found on the basis of a diagnostic radial mass flux equation that the source term for latent heat provides the largest contribution to intensification and contraction. Furthermore, it turns out that the position of the convective ring inside or outside of the RMGW is of vital importance for intensification and most likely explains the large impact of boundary layer imbalance.

Read: Frisius, T., & Lee, M. (2016). The impact of gradient wind imbalance on tropical cyclone intensification within Ooyama’s three-layer model. Journal of the Atmospheric Sciences, (2016).
Online: http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-15-0336.1

 

Date issued: 04 June 2016

The relevance of national contexts for carbon disclosure decisions of stock-listed companies: a multilevel analysis

Since 2000, a variety of initiatives have come into being with the aim of pressurizing companies to disclose their carbon emissions and other climate change related information. However, participation in carbon disclosure programs differs strongly between countries, indicating an influence of the characteristics of national regulatory contexts. The article examines how stringency and enforcement of environmental regulations on the one hand, and legal origins of financial systems on the other, explain whether firms participate in the CDP climate change disclosure program or not. Furthermore, it is asked whether multinational corporations are less affected by country-level characteristics. Our results show that both environmental regulations and legal origin are extremely relevant explanatory factors. Furthermore, while multinational firms do report more than domestic firms, we could not find that multinational corporations are less affected by the characteristics of their countries- of-origin. Our findings have implications for transparency-based initiatives as a governance tool for climate change mitigation, since they fit into some regulatory contexts better than others. Advances in voluntary disclosure seem most likely in emergent countries which tighten environmental regulations while liberalizing their economy.

Read: Grauel, J., & Gotthardt, D. (2016). The Relevance of National Contexts for Carbon Disclosure Decisions of Stock-Listed Companies: A Multilevel Analysis. Journal of Cleaner Production.
Online: http://www.sciencedirect.com/science/article/pii/S0959652616306655

Contact: Jonas Grauel (jonas.graueldummy@yahoodummy2.de), Daniel Gotthardt (daniel.gotthardtdummy@gmxdummy2.de)

 

Date issued: 01 June 2016

Dies Oecologicus—How to Foster a Whole Institutional Change with a Student-Led Project as Tipping Point for Sustainable Development at Universities

The student-led project organizing the event Dies Oecologicus, which aims for a whole institutional change by initiating a bottom-up sustainable development process, is described. Driven by the need for a more prominent role of sustainability in the university’s curriculum, the daily lives of its members, and the governance and administration of the organisation, the initiative started off as an interdisciplinary student-led project. The university-wide event was realised based on an assessment of conducted interviews with change agents (at the University of Hamburg and other universities) at all levels of the university from several disciplines and faculties. The event Dies Oecologicus has been acknowledged as a single contribution to the UN Decade Education for Sustainable Development (DESD). During the event Dies Oecologicus participants from multiple backgrounds reflected on, discussed and created possible concepts of a curriculum on ESD, student-led projects and the reduction of the ecological footprint of universities. The possible concept(s) for a curriculum on ESD was based on sessions focusing on identifying essential content, adequate didactical methods and feasible curricular realisations and integrations. Results of the project were summarised in an evaluation booklet, distributed throughout the university. This participative process has proven to be a successful strategy to overcome resistance to change, influencing current reforms, empowering change agents and establishing a network. Several changes on a personal, personnel, institutional and regional level are described.

Read: Block, M., Braßler, M., Orth, V., Riecke, M., Lopez, J. M. R., Perino, G., ... & Lamparter, M. (2016). Dies Oecologicus—How to Foster a Whole Institutional Change with a Student-Led Project as Tipping Point for Sustainable Development at Universities. In Teaching Education for Sustainable Development at University Level (pp. 341-355). Springer International Publishing.
Online: http://link.springer.com/chapter/10.1007/978-3-319-32928-4_24

Contact: Juan Miguel Rodriguez Lopez (miguel.rodriguezdummy@uni-hamburgdummy2.de)

 

Date issued: 26 May 2016

Satellite Remote Sensing of Snow Depth on Antarctic Sea Ice: An Inter-Comparison of Two Empirical Approaches

Snow depth on sea ice is a key parameter for the seasonal sea-ice thickness evolution, ocean-sea ice-atmosphere heat exchange, and for the retrieval of the sea-ice thickness using satellite altimetry. The most commonly used snow depth on sea ice product for the Southern Ocean around Antarctica is based on an empirical approach applied to satellite microwave radiometer data. Results of this approach are inter-compared with an alternative empirical approach which utilizes satellite laser altimetry. The present paper confirms results from earlier studies concerning an under-estimation of the snow depth obtained from microwave radiometry and adds that particularly the winter-to-spring evolution of the snow depth obtained from microwave radiometry is not realistic in comparison to the results from laser altimetry. Thereby the paper contributes to our knowledge about the uncertainty of snow depth on Antarctic sea ice retrieved from satellite microwave radiometry.

Read: Kern, S., & Ozsoy-Çiçek, B. (2016). Satellite Remote Sensing of Snow Depth on Antarctic Sea Ice: An Inter-Comparison of Two Empirical Approaches. Remote Sensing, 8(6), 450.
Online: http://www.mdpi.com/2072-4292/8/6/450

 

Date issued: 22 May 2016

Effect of subseabed salt domes on Tidal Residual currents in the Persian Gulf

Geological studies in the Persian Gulf (PG) have revealed the existence of subseabed salt-domes. With suitable filtering of a high-resolution PG seabed topography, it is seen that the domes leave their signature in the seabed, i.e., numerous hills and valleys with amplitudes of several tens of meters and radii from a few up to tens of kilometers. It was suspected that the “shark skin” of the PG seabed may affect the tidal residual flow. The interaction of tidal dynamics and these obstacles was investigated in a nonlinear hydrodynamic numerical tidal model of the PG. The model was first used to characterize flow patterns of residual currents generated by a tidal wave passing over symmetric, elongated and tilted obstacles. Thereafter it was applied to the entire PG. The model was forced at its open boundary by the four dominant tidal constituents residing in the PG. Each tidal constituent was simulated separately. Results, i.e., tidal residual currents in the PG, as depicted by Lagrangian trajectories reveal a stationary flow that is very rich in eddies. Each eddy can be identified with a topographic obstacle. This confirms that the tidal residual flow field is strongly influenced by the nonlinear interaction of the tidal wave with the bottom relief which, in turn, is deformed by salt-domes beneath the seabed. Different areas of maximum residual current velocities are identified for major tidal constituents. The pattern of trajectories indicates the presence of two main cyclonic gyres and several adjacent gyres rotating in opposite directions and a strong coastal current in the northern PG.

Read: Mashayekh Poul, H., Backhaus, J., Dehghani, A., & Huebner, U. Effect of subseabed salt domes on Tidal Residual currents in the Persian Gulf. Journal of Geophysical Research: Oceans.
Online: http://onlinelibrary.wiley.com/doi/10.1002/2015JC011421/abstract;jsessionid=67A8954D0E9FF9E3E44629ABBEC38DD1.f04t02

 

Date issued: 20 April 2016

Asian irrigation, African rain: Remote impacts of irrigation

Irrigation is not only vital for global food security but also constitutes an anthropogenic land use change, known to have strong effects on local hydrological and energy cycles. Using the Max Planck Institute for Meteorology's Earth System Model, we show that related impacts are not confined regionally but that possibly as much as 40% of the present-day precipitation in some of the arid regions in Eastern Africa are related to irrigation-based agriculture in Asia. Irrigation in South Asia also substantially influences the climate throughout Southeast Asia and China via the advection of water vapor and by altering the Asian monsoon. The simulated impact of irrigation on remote regions is sensitive to the magnitude of the irrigation-induced moisture flux. Therefore, it is likely that a future extension or decline of irrigated areas due to increasing food demand or declining fresh water resources will also affect precipitation and temperatures in remote regions.

Read: Vrese, P., Hagemann, S., & Claussen, M. (2016). Asian irrigation, African rain: Remote impacts of irrigation. Geophysical Research Letters, 43(8), 3737-3745.
Online: http://onlinelibrary.wiley.com/doi/10.1002/2016GL068146/abstract

Contact: Martin Claußen (martin.claussendummy@mpimet.mpgdummy2.de)

 

Date issued: 15 April 2016

The link between marine sediment records and changes in Holocene Saharan landscape: simulating the dust cycle

Marine sediment records reveal an abrupt and strong increase in dust deposition in the North Atlantic at the end of the African Humid Period about 4.9 to 5.5 ka ago. The change in dust flux has been attributed to varying Saharan land surface cover. Alternatively, the enhanced dust accumulation is linked to enhanced surface winds and a consequent intensification of coastal upwelling. Here we demonstrate for the first time the direct link between dust accumulation in marine cores and changes in Saharan land surface. We simulate the mid-Holocene (6 ka BP) and pre-industrial (1850 AD) dust cycle as a function of Saharan land surface cover and atmosphere-ocean conditions using the coupled atmosphere–aerosol model ECHAM6.1-HAM2.1. Mid-Holocene surface characteristics, including vegetation cover and lake surface area, are derived from proxy data and simulations. In agreement with data from marine sediment cores, our simulations show that mid-Holocene dust deposition fluxes in the North Atlantic were two to three times lower compared with pre-industrial fluxes. We identify Saharan land surface characteristics to be the main control on dust transport from North Africa to the North Atlantic. We conclude that the increase in dust accumulation in marine cores is directly linked to a transition of the Saharan landscape during the Holocene and not due to changes in atmospheric or ocean conditions alone.

Read: Egerer, S., Claussen, M., Reick, C., & Stanelle, T. (2016). The link between marine sediment records and changes in Holocene Saharan landscape: simulating the dust cycle. Climate of the Past, 12(4), 1009-1027.
Online: http://www.clim-past.net/12/1009/2016/

Contact: Martin Claußen (martin.claussendummy@mpimet.mpgdummy2.de)

 

Date issued: 07 April 2016

Conflict and cooperation in the water-security nexus: a global comparative analysis of river basins under climate change

This paper looks at the transboundary river basins in the world and assesses the conditions under which changes in water availability have triggered conflicts or have fostered cooperation. Based on a comprehensive review of the scientific literature on this subject, an analytical framework of the water-security nexus is developed that integrates the physical and socioeconomic pathways connecting water availability with conflict or cooperation. We apply this framework to two regions that can be considered water-related hot spots in times of climate change: the Nile River in Northeastern Africa and the Syr Darya/Amu Darya system in Central Asia. In order to reduce the likelihood of conflict over water and to promote cooperation instead it is important to understand the interactions between the physical setting, the socio-economic pressures, and the political boundary conditions in a given transboundary river system.

Read: Link, P. M., Scheffran, J., & Ide, T. (2016). Conflict and cooperation in the water‐security nexus: a global comparative analysis of river basins under climate change. Wiley Interdisciplinary Reviews: Water.
Online: http://onlinelibrary.wiley.com/doi/10.1002/wat2.1151/full

 

Date issued: 06 April 2016

Northern Hemisphere hydroclimate variability over the past twelve centuries

Accurate modelling and prediction of the local to continental-scale hydroclimate response to global warming is essential given the strong impact of hydroclimate on ecosystem functioning, crop yields, water resources, and economic security. However, uncertainty in hydroclimate projections remains large, in part due to the short length of instrumental measurements available with which to assess climate models. Here we present a spatial reconstruction of hydroclimate variability over the past twelve centuries across the Northern Hemisphere derived from a network of 196 at least millennium-long proxy records. We use this reconstruction to place recent hydrological changes and future precipitation scenarios in a long-term context of spatially resolved and temporally persistent hydroclimate patterns. We find a larger percentage of land area with relatively wetter conditions in the ninth to eleventh and the twentieth centuries, whereas drier conditions are more widespread between the twelfth and nineteenth centuries. Our reconstruction reveals that prominent seesaw patterns of alternating moisture regimes observed in instrumental data across the Mediterranean, western USA, and China have operated consistently over the past twelve centuries. Using an updated compilation of 128 temperature proxy records, we assess the relationship between the reconstructed centennial-scale Northern Hemisphere hydroclimate and temperature variability. Even though dry and wet conditions occurred over extensive areas under both warm and cold climate regimes, a statistically significant co-variability of hydroclimate and temperature is evident for particular regions. We compare the reconstructed hydroclimate anomalies with coupled atmosphere–ocean general circulation model simulations and find reasonable agreement during pre-industrial times. However, the intensification of the twentieth-century-mean hydroclimate anomalies in the simulations, as compared to previous centuries, is not supported by our new multi-proxy reconstruction. This finding suggests that much work remains before we can model hydroclimate variability accurately, and highlights the importance of using palaeoclimate data to place recent and predicted hydroclimate changes in a millennium-long context.

Read: Ljungqvist, F. C., Krusic, P. J., Sundqvist, H. S., Zorita, E., Brattström, G., & Frank, D. (2016). Northern Hemisphere hydroclimate variability over the past twelve centuries. Nature, 532(7597), 94-98.
Online: http://www.nature.com/nature/journal/v532/n7597/abs/nature17418.html

Contact: Eduardo Zorita (eduardo.zorita@hzg.de)

Date issued: June 2016

Extremes and Recurrence in Dynamical Systems

Written by a team of international experts, Extremes and Recurrence in Dynamical Systems presents a unique point of view on the mathematical theory of extremes and on its applications in the natural and social sciences. Featuring an interdisciplinary approach to new concepts in pure and applied mathematical research, the book skillfully combines the areas of statistical mechanics, probability theory, measure theory, dynamical systems, statistical inference, geophysics, and software application. Emphasizing the statistical mechanical point of view, the book introduces robust theoretical embedding for the application of extreme value theory in dynamical systems.

Read: Lucarini, V., D. Faranda, A.C. Gomes Monteiro Moreira de Freitas, J.M. Milhazes de Freitas, M. Holland, T. Kuna, M. Nicol, M. Todd and S. Vaienti (2016): Extremes and Recurrence in Dynamical Systems.
Online: http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1118632192.html
Contact: Valerio Lucarini (valerio.lucarinidummy@uni-hamburgdummy2.com)

 

Date issued: 28 May 2016

High-resolution simulations for Vietnam - Methodology and evaluation of current climate

An ensemble of high-resolution climate projections for Vietnam was generated using the regional climate models (RCMs) CCAM and RegCM4. In total six CMIP5 global climate models (GCMs) driven by two representative concentration pathways (RCP4.5 and 8.5) were downscaled with CCAM in a two-step approach. First, a 50-km global uniform-grid version of CCAM was driven by bias- and variance corrected GCM sea surface temperatures and sea ice concentrations. Thereafter, a stretched-grid version of CCAM with a resolution of 10 km over Vietnam is used to downscale the 50-km results employing spectral nudging. In a second approach two CMIP5-GCMs driven by RCP4.5 and 8.5 were downscaled with the limited-area RCM RegCM4 down to a resolution of 20 km. The boundary conditions were provided by global 100-km uniform-grid CCAM simulations. The current paper describes the downscaling methodology and evaluates the simulations for the current climate using different observational datasets.

Read: Katzfey J., K. Nguyen, J. McGregor, P. Hoffmann, S. Ramasamy, H. T. Nguyen, H. V. Nguyen, K. V. Mai, T. V. Nguyen, K. T. Ba, T. V. Van, T. V. Phan, T. Q. Nguyen, N. D. Thanh and L. T. Trinh (2016): High-resolution simulations for Vietnam - Methodology and evaluation for current climate. Asia-Pacific Journal of Atmospheric Science, Vol. 52(2). doi: 10.1007/s13143-016-0011-2.
Online:
http://link.springer.com/article/10.1007%2Fs13143-016-0011-2http://link.springer.com/article/10.1007%2Fs13143-016-0011-2

Contact: Peter Hoffmann (
peter.hoffmanndummy@uni-hamburgdummy2.depeter.hoffmanndummy@uni-hamburgdummy2.de
)

 

Date issued: 26 May 2016

Climate change scenarios for Tibetan Plateau summer precipitation based on canonical correlation analysis

Precipitation in the Tibetan Plateau (TP) reaches its peak in summer. The seasonal projection skill of a statistical downscaling model (SDM) for summer precipitation in the TP was compared with that of direct model output. The SDM, which is based on canonical correlation analysis (CCA), significantly increased the projection skill. The CCA reveals the flow patterns behind the seasonal projection skill of summer precipitation in the TP between 1961 and 2012 and quantifies its relative contributions. East Asia 500 hPa geopotential height (ZG500), tropical Indian Ocean sea surface temperature (SST) and east Asia 850 hPa meridional water vapour flux (MWVF850), obtained from the Max Planck Institute Earth System Model, low-resolution (MPI-ESM-LR) simulations for phase 5 of the Coupled Model Intercomparison Project under the representative concentration pathway (RCP) 2.6, RCP4.5 and RCP8.5 scenarios are considered as potential predictors. The SDMs are established in 1961–2005, validated in 2006–2012 and applied in 2013–2100. The ensemble canonical correlation (ECC) is also applied to improve projection skill. The following results are obtained: (1) The SDM projection skill for each predictor is higher than that of the MPI-ESM-LR climate model, and ECC performs even better. (2) Spatial correlation patterns of different predictors with influence on the TP are well recognized by CCA. The high relevance of ZG500 can be explained by the thermal adaptation theory, that of SST exhibits a canonical Indian Ocean Dipole mode, and MWVF850 shows a simple water vapour link. (3) The amount of summer precipitation in the TP will slightly decrease under RCP2.6 by −3.4 mm decade−1, whereas RCP4.5 and RCP8.5 reveal an increase by 2.4 and 18.4 mm decade−1, respectively.

Read: Chen, X., Q. You, F. Sielmann and N. Ruan (2016): Climate change scenarios for Tibetan Plateau summer precipitation based on canonical correlation analysis. Int. J. Climatol. doi: 10.1002/joc.4778.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/joc.4778/fullhttp://onlinelibrary.wiley.com/doi/10.1002/joc.4778/full
Contact: Frank Sielmann (
frank.sielmanndummy@uni-hamburgdummy2.defrank.sielmanndummy@uni-hamburgdummy2.de)

 

Date issued: 11 May 2016

Seasonal cycle of precipitation over major river basins in South and Southeast Asia: A review of the CMIP5 climate models data for present climate and future climate projections

We review the skill of thirty coupled climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) in terms of reproducing properties of the seasonal cycle of precipitation over the major river basins of South and Southeast Asia (Indus, Ganges, Brahmaputra and Mekong) for the historical period (1961–2000). We also present how these models represent the impact of climate change by the end of century (2061–2100) under the extreme scenario RCP8.5. First, we assess the models' ability to reproduce the observed timings of the monsoon onset and the rate of rapid fractional accumulation (RFA) slope — a measure of seasonality within the active monsoon period. Secondly, we apply a threshold-independent seasonality index (SI) — a multiplicative measure of precipitation (P) and extent of its concentration relative to uniform distribution (relative entropy — RE).

Read: Hasson, S., S. Pascale, V. Lucarini & J. Böhner (2016): Seasonal cycle of precipitation over major river basins in South and Southeast Asia: A review of the CMIP5 climate models data for present climate and future climate projections. Atmospheric Research.
Online:
http://www.sciencedirect.com/science/article/pii/S016980951630117Xhttp://www.sciencedirect.com/science/article/pii/S016980951630117X
Contact: Shabeh ul Hasson (Shabeh.hassondummy@uni-hamburgdummy2.deShabeh.hassondummy@uni-hamburgdummy2.de)

 

Date issued: 10 May 2016

Actors and networks in resource conflict resolution under climate change in rural Kenya

This article examines how climate change affects rural conflict resolution dynamics and institutions, in the context of conflict-sensitive adaptation. The study of social network data reveals three forms of fused conflict resolution arrangements in Loitoktok, Kenya where extension officers, council of elders, local chiefs and private investors are potential conduits of knowledge. Efficiency of rural conflict resolution can be enhanced by diversification among actors, networks and institutions.

 

Read: Ngaruiya, G. W. and  J. Scheffran (2016): Actors and Networks in Resource Conflict Resolution under Climate Change in Rural Kenya. Earth System Dynamics, 7(2), 441-452. doi: 10.5194/esd-7-441-2016.
Online:
http://www.earth-syst-dynam.net/7/441/2016/esd-7-441-2016-discussion.html
Contact: Jürgen Scheffran (
juergen.scheffrandummy@uni-hamburgdummy2.dejuergen.scheffrandummy@uni-hamburgdummy2.de)

 

Date issued: 04 May 2016

A comparison of two ensemble generation methods using oceanic singular vectors and atmospheric lagged initialization for decadal climate prediction

The sensitivity of ensemble spread and forecast skill scores of decadal predictions to details of the ensemble generation is investigated by incorporating uncertainties of ocean initial conditions using ocean singular-vector-based (OSV) perturbations. Results are compared to a traditional atmospheric lagged initialization (ALI) method. Both sets of experiments are performed using the coupled MPI-ESM model initialized from the GECCO2 ocean synthesis. The OSVs are calculated from a linear inverse model based on a historical MPI-ESM run. During the first three lead years, the sea surface temperature spread from ALI-hindcasts appears to be strongly underestimated, while OSV-hindcasts show a more realistic spread. However, for later lead times (second pentad of hindcasts), the spread becomes overestimated for large areas of the ocean in both ensembles. Yet, for integrated measures such as the North Atlantic SST and Atlantic meridional overturning circulation, the spread of OSV-hindcasts is overestimated at initial time and reduces over time. The spread reliability measures are shown to be sensitive to the choice of the verification data set. In this context, it is found that HadISST tends to underestimate the variability of SST as compared to Reynolds SST and satellite observations. In terms of forecast skill for surface air temperature, SST and ocean heat content, OSV-hindcasts show improvement over ALI-hindcasts over the North Atlantic Ocean up to lead year five.

Read: Marini, C., I. Polkova, A. Köhl and D. Stammer (2016): A comparison of two ensemble generation methods using oceanic singular vectors and atmospheric lagged initialization for decadal climate prediction. Mon. Wea. Rev. doi: 10.1175/MWR-D-15-0350.1.
Online:
http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-15-0350.1http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-15-0350.1

Contact: Iuliia Polkova (
iuliia.polkovadummy@uni-hamburgdummy2.deiuliia.polkovadummy@uni-hamburgdummy2.de
)

 

Date issued: 02 May 2016

Atmospheric response to Indian Ocean Dipole forcing: changes of Southeast China winter precipitation under global warming

To investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the subsequent winter precipitation in Southeast China (SEC), observed fields of monthly precipitation, sea surface temperature (SST) and atmospheric circulation are subjected to a running and a maximum correlation analysis. The results show a significant change of the relevance of IOD for the early modulation of SEC winter precipitation in the 1980s. After 1980, positive correlations suggest prolonged atmospheric responses to IOD forcing, which are linked to an abnormal moisture supply initiated in autumn and extended into the subsequent winter. Under global warming two modulating factors are relevant: (1) an increase of the static stability has been observed suppressing vertical heat and momentum transports; (2) a positive (mid-level) cloud-radiation feedback jointly with the associated latent heating (apparent moisture sink Q2) explains the prolongation of positive as well as negative SST anomalies by conserving the heating (apparent heat source Q1) in the coupled atmosphere–ocean system. During the positive IOD events in fall (after 1980) the dipole heating anomalies in the middle and lower troposphere over the tropical Indian Ocean are prolonged to winter by a positive mid-level cloud-radiative feedback with latent heat release. Subsequently, thermal adaptation leads to an anticyclonic anomaly over Eastern India overlying the anomalous cooling SST of the tropical Eastern Indian Ocean enhancing the moisture flow from the tropical Indian Ocean through the Bay of Bengal into South China, following the northwestern boundary of the anticyclonic circulation anomaly over east India, thereby favoring abundant precipitation in SEC.

Read: Zhang, L., F. Sielmann, K. Fraedrich and X. Zhi (2016): Atmospheric response to Indian Ocean Dipole forcing: Changes of Southeast China winter precipitation under global warming. Clim. Dyn. doi: 10.1007/s00382-016-3152-1.
Online:
http://link.springer.com/article/10.1007/s00382-016-3152-1http://link.springer.com/article/10.1007/s00382-016-3152-1
Contact: Frank Sielmann (
frank.sielmanndummy@uni-hamburgdummy2.defrank.sielmanndummy@uni-hamburgdummy2.de)

 

Date issued: 28 April 2016

Looking beyond stratification: a model-based analysis of the biological drivers of oxygen deficiency in the North Sea

We used the ECOHAM5 model to provide a consistent picture of the physical and biological drivers of oxygen deficiency in the North Sea. Regions susceptible to oxygen deficiency are characterised by low tidal mixing and moderate water depth (~40m). Variations in upper layer productivity drive the year-to-year variability of bottom oxygen conditions. The model-based analysis reveals that benthic and pelagic remineralisation account for 90% of bottom oxygen consumption observed at North Dogger.

Read: Große, F., N. Greenwood, M. Kreus, H.-J. Lenhart, D. Machoczek, J. Pätsch, L. Salt, and H. Thomas (2016): Looking beyond stratification: a model-based analysis of the biological drivers of oxygen deficiency in the North Sea. Biogeosciences, 13, 2511-2535. doi: 10.5194/bg-13-2511-2016.
Online:
http://www.biogeosciences.net/13/2511/2016/bg-13-2511-2016.htmlhttp://www.biogeosciences.net/13/2511/2016/bg-13-2511-2016.html
Contact: Fabian Große (
fabian.grossedummy@uni-hamburgdummy2.defabian.grossedummy@uni-hamburgdummy2.de)

 

Date issued: 26 April 2016

Climate migrants as protestors? Dispelling misconceptions about global environmental change in pre-revolutionary Syria

For a growing number of commentators, the Syrian uprising is explained by a prolonged drought period immediately preceding the outbreak of conflict in Syria in 2011. In this narrative, the marginalized ‘climate migrants’ are seen as a decisive factor for the onset of conflict. In this paper the author dispels these assumptions by arguing for a more complex approach that takes into consideration pre-existing internal migration patterns – social, demographic, political and economic drivers of migration – as well as new local-level data showing that ‘climate migrants’ could not have orchestrated an uprising of this magnitude for lack of reliable social networks.

Read: Fröhlich, C. (2016): Migrants as Protestors? Dispelling Misconceptions about Global Environmental Change in Pre-Revolutionary Syria. In: Contemporary Levant, Vol. 1, Nr. 1, 38-50, doi: 10.1080/20581831.2016.1149355.
Online:
http://www.tandfonline.com/doi/full/10.1080/20581831.2016.1149355http://www.tandfonline.com/doi/full/10.1080/20581831.2016.1149355
Contact: Christiane Fröhlich (
froehlichdummy@ifshdummy2.defroehlichdummy@ifshdummy2.de)

 

Date issued: 26 April 2016

Modelling tidal influence on sea breezes with models of different complexity

Tides influence both the formation and development of sea breezes. The present study investigates this influence to decide which model complexity is needed to reproduce the main influence of tides in a numerical model of coastal meteorology. The results show that the main influence of tides originates from a change in the mudflat heat budget through flooding and drying. The influence of tidal currents on the surface wind is small. Therefore, it is sufficient to simulate surface cover changes in an atmospheric model without a full coupling to an ocean model to consider the influence of oceanic tides on mesoscale meteorology.

Read: Fischereit, J., K.H. Schlünzen, A.M.U.  Gierisch, D. Grawe, and R. Petrik (2016): Modelling tidal influence on sea breezes with models of different complexity. Meteorologische Zeitschrift, doi: 10.1127/metz/2016/0703.
Online: http://www.schweizerbart.de/papers/metz/detail/prepub/85651/Modelling_tidal_influence_on_sea_breezes_with_mode?af=crossref
Contact: Jana Fischereit (Jana.Fischereitdummy@uni-hamburgdummy2.de)

 

Date issued: 19 April 2016

Three dimensional chaotic advection by mixed layer baroclinic

Three dimensional (3D) Finite Time Lyapunov Exponents (FTLEs) are computed from numerical simulations of a freely evolving mixed layer (ML) front in a zonal channel undergoing baroclinic instability. The 3D FTLEs show a complex structure, with features that are less defined than the two-dimensional (2D) FTLEs, suggesting that stirring is not confined to the edges of vortices and along filaments and posing significant consequences on mixing. The magnitude of the FTLEs is observed to be strongly determined by the vertical shear. A scaling law relating the local FTLEs and the nonlocal density contrast used to initialize the ML front is derived assuming thermal wind balance. The scaling law only converges to the values found from the simulations within the pycnocline, while it displays differences within the ML, where the instabilities show a large ageostrophic component. The probability distribution functions of 2D and 3D FTLEs are found to be non Gaussian at all depths. In the ML, the FTLEs wavenumber spectra display -1 slopes, while in the pycnocline, the FTLEs wavenumber spectra display -2 slopes, corresponding to frontal dynamics. Close to the surface, the geodesic Lagrangian Coherent Structures (LCSs) reveal a complex stirring structure, with elliptic structures detaching from the frontal region. In the pycnocline, LCSs are able to detect filamentary structures that are not captured by the Eulerian fields.

Read: Mukiibi, D., G. Badin and N. Serra (2016): Three dimensional chaotic advection by mixed layer baroclinic. Journal of Physical Oceanography, 46, 1509-1529. doi: 10.1175/JPO-D-15-0121.1.
Online:
http://journals.ametsoc.org/doi/10.1175/JPO-D-15-0121.1http://journals.ametsoc.org/doi/10.1175/JPO-D-15-0121.1
Contact:
Gualiero Badin (gualtiero.badindummy@uni-hamburgdummy2.degualtiero.badindummy@uni-hamburgdummy2.de)

 

Date issued: 13 April 2016

An automatic precipitation phase distinction algorithm for optical disdrometer data over the global ocean

OceanRAIN (Ocean Rainfall And Ice-phase precipitation measurement Network) provides a comprehensive statistical basis of in situ precipitation reference data from optical disdrometers deployed on various research vessels. Deriving the precipitation rate for rain and snow requires a priori knowledge of the precipitation phase (PP). We present an automatic PP distinction algorithm using more than four years of RV Polarstern data covering all climatic regions of the Atlantic Ocean. We find that the combination of air temperature, relative humidity and 99th percentile of the particle diameter predicts best the PP. We introduce two independent PP distributions for rain and snow and provide an objective PP probability for each PP at 1 min resolution.

Read: Burdanowitz, J., C. Klepp and S. Bakan (2016): An automatic precipitation-phase distinction algorithm for optical disdrometer data over the global ocean. Atmos. Meas. Tech., 9, 1637-1652. doi: 10.5194/amt-9-1637-2016.
Online:
http://www.atmos-meas-tech.net/9/1637/2016/http://www.atmos-meas-tech.net/9/1637/2016/
Contact: Jörg Burdanowitz (
joerg.burdanowitzdummy@mpimet.mpgdummy2.dejoerg.burdanowitzdummy@mpimet.mpgdummy2.de)

 

Date issued: 07 April 2016

Conflict and cooperation in the water-security nexus: a global comparative analysis of river basins under climate change

Adequate fresh water availability is an important factor for human security in many parts of the world. In transboundary river basins, decreased water supply due to local environmental change and global climate change and increased water demand due to growing populations and continued economic development can aggravate water scarcity. Contrary to the claim that water scarcity may result in an increased risk of armed conflict, there is no simple relationship between freshwater availability and violent conflict. Other crucial factors need to be taken into consideration that also directly influence resource availability and personal human well-being. In this review, we assess the scientific literature on conflict and cooperation in transboundary river systems. Most international river basins are already jointly managed by the riparians, but successful management in times of climate change necessitates the inclusion of more factors besides mere allocation schemes. On the basis of a substantial body of literature on the management of transboundary watersheds, an analytical framework of the water-security nexus is developed that integrates the physical and socioeconomic pathways connecting water availability with conflict or cooperation. This framework is subsequently applied to two transboundary river basins—the Nile River and the Syr Darya/Amu Darya—as they represent two world regions that could become future water hot spots. An improved understanding of the developments leading to water conflicts and their interaction can help to successfully reduce the risk of water conflicts in these regions and to move toward increased cooperation among the riparians of transboundary river systems.

Read: Link, P.M., J. Scheffran and T. Ide (2016): Conflict and cooperation in the water-security nexus: a global comparative analysis of river basins under climate change, WIREs Water. doi: 10.1002/wat2.1151.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/wat2.1151/abstracthttp://onlinelibrary.wiley.com/doi/10.1002/wat2.1151/abstract
Contact: Michael Link (Michael.linkdummy@uni-hamburgdummy2.de)

 

Date issued: 06 April 2016

Impact of eustatic and tectonic processes on the southeastern Mediterranean shelf during the last one million years: Quantitative reconstructions using a foraminiferal transfer function

We present results of a foraminiferal transfer function aiming at the reconstruction of relative sea level in the southeastern Mediterranean shelf during the past one million years. The deepest paleo water depths were reconstructed for the earliest sea-level highstands recorded in the sediment records (MIS 27? and MIS 29?) in the down-faulted boreholes due to tectonic movements, whereas the younger interglacial sedimentary units (MIS 25?, 13, 11, 7, 5.5 and 1) were mostly deposited at around 15 m water depths or slightly deeper during MIS 7. Our paleowater depth estimates demonstrate a shallowing trend during the Holocene, generally matching other regional Mediterranean sea-level records.

Read: Avnaim-Katav, S., Y. Milker, G. Schmiedl, D. Sivan, O. Hyams-Kaphzan, A. Sandler and A. Almogi-Labin (2016): Impact of eustatic and tectonic processes on the southeastern Mediterranean shelf during the last one million years: Quantitative reconstructions using a foraminiferal transfer function. Marine Geology, 376, 26-38. doi: 10.1016/j.margeo.2016.03.010.
Online:
http://www.sciencedirect.com/science/article/pii/S0025322716300287http://www.sciencedirect.com/science/article/pii/S0025322716300287
Contact: Gerhard Schmiedl (
laura.niederdrenkdummy@mpimet.mpgdummy2.degerhard.schmiedldummy@uni-hamburgdummy2.de)

 

Date issued: 5 April 2016

Contributing to WUDAPT: A Local Climate Zone Classification of Two Cities in Ukraine

 

Local Climate Zones (LCZs) divide the urban landscape into homogeneous types based on structure, cover, construction materials and human activities. They are used as a standardized way of capturing the basic urban form of cities in the WUDAPT initiative. This paper assesses the transferability of the LCZ concept to two Ukrainian cities, i.e. Kyiv and Lviv, which differ in urban form and topography, and considers different ways to validate and verify this classification scheme. An accuracy of 64% was achieved for Kyiv using an independent validation dataset while a comparison of the LCZ maps with the GlobeLand30 land cover map resulted in a match that was greater than 75% for both cities.

 

Read: Danylo, .O, L. See, B. Bechtel, D. Schepaschenko and S. Fritz (2016): Contributing to WUDAPT: A Local Climate Zone Classification of Two Cities in Ukraine. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. Doi: 10.1109/JSTARS.2016.2539977

Online: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7447735http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7447735

 

Date issued: 29 March 2016

Classification of Local Climate Zones Using SAR and Multispectral Data in an Arid Environment

 

There is an urgent need for more detailed spatial information on cities globally. As part of the WUDAPT (World Urban Database and Access Portal Tools) initiative, a simple workflow has been developed to characterize settlements using the Local Climate Zone (LCZ) scheme. In this paper, the methodology is extended to examine the effect of adding SAR (Synthetic Aperture Radar) data from Sentinel 1. Using the city of Khartoum as a case study, the results show that combining multi-spectral and SAR data slightly improves the overall performance.

 

Read: Bechtel, B., L. See, G. Mills and M. Foley (2016): Classification of Local Climate Zones Using SAR and Multispectral Data in an Arid Environment. IEEE Journal of selected topics in applied earth observations and remote sensing, vol. 9, no. 5, p. 1-9. doi: 10.1109/JSTARS.2016.2531420.

Online: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7442773&newsearch=true&queryText=Classification%20of%20Local%20Climate%20Zones%20using%20SAR%20and%20multi-spectral%20data%20in%20an%20arid%20environment

 

Date issued: 21 March 2016

A distal 140 kyr sediment record of Nile discharge and East African monsoon variability

Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the eastern Mediterranean Sea (EMS) during the last 140 kyr. The long-term climate regime was governed by the African monsoon that caused major African humid periods (AHPs) with enhanced sediment discharge at 132 to < 126 (AHP 5), 116 to 99 (AHP4), and 89 to 77 ka (AHP3). They lasted much longer than the formation of the related sapropel layers S5 (> 2 kyr), S4 (3.5 kyr), and S3 (5 kyr). Feedback mechanisms between vegetation cover and sediment discharge of the Nile are detectable but of minor importance for the sedimentary record in the southeastern Mediterranean Sea during the investigated African humid periods.

Read: Ehrmann, W., G. Schmiedl, M. Seidel, S. Krüger and H. Schulz (2016): A distal 140 kyr sediment record of Nile discharge and East African monsoon variability. Climate of the Past, 12, 713-727. doi: 10.5194/cp-12-713-2016.
Online:
http://www.clim-past.net/12/713/2016/http://www.clim-past.net/12/713/2016/
Contact: Gerhard Schmiedl (laura.niederdrenkdummy@mpimet.mpgdummy2.degerhard.schmiedldummy@uni-hamburgdummy2.de)

 

Date issued: 09 March 2016

Brine formation recorded by stable isotopes of Recent benthic foraminifera in Storfjorden, Svalbard: palaeoceanographical implications

We discuss water stable oxygen isotopes and stable carbon isotopes of dissolved inorganic carbon of brine-enriched shelf water (BSW) from Storfjorden (southern Svalbard) in comparison to the stable isotope composition of Recent benthic foraminifera calcified in the same water. Low stable carbon and high stable oxygen isotope values in epibenthic foraminifera indicate modern brine production in Storfjorden. The recorded signals are in strong contrast to what is anticipated from palaeoceanographic proxy records as the stable oxygen isotope signature of meteoric water is very low. We believe that the high stable oxygen isotope values of brine water is a result of the fact that it is most often high-salinity water that becomes sufficiently dense to form BSW, and fresh water from glaciers or groundwater does not significantly contribute.

Read: Mackensen, A. and G. Schmiedl (2016): Brine formation recorded by stable isotopes of Recent benthic foraminifera in Storfjorden, Svalbard: palaeoceanographical implications. Boreas. doi: 10.1111/bor.12174.
Online: http://onlinelibrary.wiley.com/doi/10.1111/bor.12174/fullhttp://onlinelibrary.wiley.com/doi/10.1111/bor.12174/full
Contact: Gerhard Schmiedl (laura.niederdrenkdummy@mpimet.mpgdummy2.degerhard.schmiedldummy@uni-hamburgdummy2.de)

 

Date issued: 03 March 2016

Modeling the Zeeman effect in high altitude SSMIS channels for numerical weather prediction profiles: comparing a fast model and a line-by-line model

 

The Zeeman effect is an important spectroscopic effect that influences the shape of spectral lines at high altitudes. So far it was quite poorly represented in radiative transfer models, with the consequence that some existing satellite data for temperature in the mesosphere could not be used. In the longer term, the new model will allow the use of these data as a climate data record. This is very valuable, since data about these altitudes so far are very sparse.

 

Read: Larsson, R., M. Milz, P. Rayer, R. Saunders, W. Bell, A. Booton, S. A. Buehler, P. Eriksson and V. John (2016): Modeling the Zeeman effect in high altitude SSMIS channels for numerical weather prediction profiles: comparing a fast model and a line-by-line model. Atmos. Meas. Tech., 9, 841–857. doi: 10.5194/amt-9-841-2016.
Online:
http://www.atmos-meas-tech.net/9/841/2016/http://www.atmos-meas-tech.net/9/841/2016/

 

Date issued: 02 March 2016

Klimaschutz als Medienwirkung. Eine kommunikationswissenschaftliche Studie zur Konzeption, Rezeption und Wirkung eines Online-Spiels zum Stromsparen.

Statt Menschen mit Katastrophenszenarien zum Klimaschutz "wachzurütteln" oder ihnen mehr Wissen über den Klimawandel vermitteln zu wollen, schlägt der hier vorgestellte medienkonzeptuelle Ansatz einen anderen Weg vor. Er macht Arbeiten aus der Lern- und Lehrforschung sowie des Interactive Storytelling nutzbar. Alltagsnahe Entscheidungsszenarien werden im Rahmen eines Online-Spiels inszeniert und die Rezipienten können erproben, welche Handlungsoption wie viel Geld- und CO2-Ersparnisse erbringt. Die Wirkungshypothesen werden theoretisch hergeleitet und mit Hilfe eines Mehrmethodenansatzes im Rahmen einer quantitativen Online-Evaluationsstudie (n = 287) geprüft. Die Ergebnisse verdeutlichen die zentrale Bedeutung des Alltagsbezugs. Statt den Klimawandel als unabwendbare Katastrophe darzustellen, ist es wesentlich erfolgversprechender, konkrete Handlungsalternativen im Alltag spielerisch erfahrbar zu machen und Charaktere darzustellen, die in realistischen Entscheidungsszenarien zwischen Klimaschutz und kurzfristigem Komfortbedürfnis schwanken. Dadurch wird eine kritische Reflexion eigener Handlungsspielräume ermöglicht.

Read: Hoppe, I. (2016): Klimaschutz als Medienwirkung. Eine kommunikationswissenschaftliche Studie zur Konzeption, Rezeption und Wirkung eines Online-Spiels zum Stromsparen. Herausgegeben von Jens Wolling, Mike S. Schäfer, Heinz Bonfadelli & Oliver Quiering, in der Buchreihe „NEU – Nachhaltigkeits-, Energie- und Umweltkommunikation“ (Open Access Reihe).
Online: http://neu-kommunikation.de/27-0-Klimaschutz.htmlhttp://neu-kommunikation.de/27-0-Klimaschutz.html
Contact: Imke Hoppe (
Imke.Hoppedummy@uni-hamburgdummy2.deImke.Hoppedummy@uni-hamburgdummy2.de)

 

Date issued: 24 February 2016

Toward a constructivist understanding of socio-environmental conflicts

The links between environmental degradation, renewable resource scarcity, and conflict are still poorly understood. One reason for this is the positivist–rationalist bias which is characteristic of the mainstream literature on socio-environment conflicts but has largely remained unaddressed so far. Many studies are therefore unable to utilize insights from environmental sociology, constructivist conflict research, and political ecology. Drawing on this literature and discourse theory, the article develops a constructivist understanding of socio-environmental conflicts. The proposed framework highlights the relevance of discursively constructed identities, situation assessments, and interests for understanding the dynamics of such conflicts. The plausibility of the framework across different contexts is demonstrated by a discussion of the Israeli–Palestinian water conflict and forest conflicts in northern Thailand.

Read: Ide, T. (2016): Toward a Constructivist Understanding of Socio-Environmental Conflicts. Civil Wars, 18(1), 69-90. doi: 10.1080/13698249.2016.1144496.
Online:
http://www.tandfonline.com/doi/abs/10.1080/13698249.2016.1144496http://www.tandfonline.com/doi/abs/10.1080/13698249.2016.1144496
Contact: Tobias Ide (tobias.idedummy@uni-hamburgdummy2.de)

 

Date issued: 13 February 2016

Der Vertrag von Paris: Klima am Wendepunkt?

Als „Wunder von Paris“ wird der Weltklimavertrag gefeiert. Bereits die Tatsache, dass sich 195 Staaten bei einer derart komplexen Frage auf ein völkerrechtlich verbindliches Abkommen einigen konnten, ist ein historischer klimadiplomatischer Erfolg. Anders als im Kyoto-Protokoll, das nur für einige Industrieländer maßgeblich war, werden mit dem neuen Abkommen Regeln einer gemeinsamen Klimapolitik für alle Staaten aufgestellt. Weltweit gab es viel Zustimmung, aber auch berechtigte Kritik. Reichen die Beschlüsse aus, werden sie überhaupt erfüllt? Die Umsetzung der Pariser Vereinbarung hängt von allen Ebenen des internationalen Systems ab, von der globalen über die nationale bis hin zur lokalen Ebene.

Read: Scheffran, J. (2016): Der Vertrag von Paris: Klima am Wendepunkt?, WeltTrends - Das außenpolitische Journal, Nr. 112, 24(2): 4-9.
Online: http://welttrends.de/res/uploads/WeltTrends-112-S%C3%BCdsee-real-Editorial-Inhalt.pdf

Contact: Jürgen Scheffran (rgen.Scheffrandummy@uni-hamburgdummy2.de)

 

Date issued: 03 February 2016

Assessing Risk Perceptions and Attitude among Cotton Farmers: A Case of Punjab Province, Pakistan

Based on a farm household survey of 480 farmers, this study aims to investigate the farmers' attitude and perceptions of various kinds of risks to which cotton crop is exposed in Pakistan. Equally Likely Certainty Equivalent (ELCE) and risk matrix methods are used to determine risk attitude and risk perceptions respectively, while the determinants of farmers' attitude and perceptions are also analyzed by using probit model.

Read: Iqbal, M. A., Q. Ping, M. Abid, S. Muhammad Muslim Kazmi, and M. Rizwan (2016): Assessing Risk Perceptions and Attitude among Cotton Farmers: A Case of Punjab Province, Pakistan. International Journal of Disaster Risk Reduction. doi: http://dx.doi.org/10.1016/j.ijdrr.2016.01.009http://dx.doi.org/10.1016/j.ijdrr.2016.01.009.
Online:
http://www.sciencedirect.com/science/article/pii/S2212420915301515http://www.sciencedirect.com/science/article/pii/S2212420915301515

Contact: Muhammand Abid (
muhammad.abiddummy@uni-hamburgdummy2.demuhammad.abiddummy@uni-hamburgdummy2.de)

 

Date issued: 03 February 2016

Stable isotope composition of deep-sea benthic foraminifera under contrasting trophic conditions in the western Mediterranean Sea

We have evaluated the environmental and biological processes affecting the stable oxygen and carbon isotope composition of live and dead tests of different benthic foraminiferal species from the western Mediterranean Sea. The recorded isotope signatures mirror the average microhabitat depth of each species and reflect the specific gradients in the stable carbon isotope composition of pore water dissolved inorganic carbon (DIC). Maximum stable carbon isotope gradients in pore water DIC of up to 2.3‰ were estimated under the influence of meso- to eutrophic conditions in the Alboran Sea. Considering the influence of ontogenetic effects, the stable carbon isotope signal of the shallow infaunal Uvigerina mediterranea appears particularly suitable as a proxy for quantitative reconstructions of past organic matter fluxes.

Read: Theodor, M., G. Schmiedl and A. Mackensen (2016): Stable isotope composition of deep-sea benthic foraminifera under contrasting trophic conditions in the western Mediterranean Sea, Marine Micropaleontology, 124, pp. 16-28. doi: 10.1016/j.marmicro.2016.02.001.
Online:
http://www.sciencedirect.com/science/article/pii/S0377839816300056http://www.sciencedirect.com/science/article/pii/S0377839816300056
Contact:
Marc Theodor (
marc.theodordummy@uni-hamburgdummy2.demarc.theodordummy@uni-hamburgdummy2.de)

 

Date issued: February 2016

Stadt – Land – Krieg – Unsicherheit in urbanen Gewalträumen

Dem Wechselspiel zwischen Stadt und Land kam und kommt in Kriegen oftmals eine wichtige Rolle zu. Aufgrund der Bevölkerungsdichte, Versorgungsinfrastruktur und Machtkonzentration sind Städte verwundbare Ziele von Gewalthandlungen, die erhebliche Schutzmaßnahmen erfordern. Ausgehend von der zunehmenden Urbanisierung und damit verbundener Dynamiken der Unsicherheit, analysiert der Beitrag Trends von Stadtkriegen und militärischen Interventionen sowie der Abwehr, Abschottung und Überwachung, um Metropolen vor gewaltinduzierten Sicherheitsrisiken zu bewahren.

Read: Scheffran, J. (2016): Stadt - Land - Krieg - Unsicherheit in urbanen Gewalträumen. Wissenschaft und Frieden, 2, 6-10.
Online:
http://www.wissenschaft-und-frieden.de/seite.php?artikelID=2116
Contact: Jürgen Scheffran (
rgen.Scheffrandummy@uni-hamburgdummy2.de)

 

Date issued: February 2016

Climate dynamics on watershed scale: along the rainfall-runoff chain

Climate regimes of watersheds are determined by the rainfall-runoff chain, which comprises processes of a wide range of time and space scales. They are presented here in geographical and eco-hydrological state spaces combining observations and minimalist concepts. (i) Water supply and demand govern the rainfall-runoff chain: Rainfall provides the water supply, net radiation represents the water demand which, related to water supply, separates water from energy limited regimes and determines the discharge as the probability of rainfall reaching the soil water reservoir. This macro-state of the rainfall-runoff chain is described by an empirical equation of state and derived by a (micro-state) biased coinflip Ansatz. (ii) Eco-hydrologic spaces spanned by water and energy fluxes or flux ratios, embed the states of the rainfall-runoff chain as occurrence probabilities and their time changes as trajectories. Tracers, like vegetation-greenness, can also be included to estimate watershed resilience and, based on the trajectories, to attribute the changes to external (or climate) and internal (or anthropogenic) causes. (iii) Geo-morphological patterns like the area ratios of closed lakes (lake/basin), soil moisture storage of watersheds, and drainage densities of river systems, can be functionally related to eco-hydrological climates. Suitable minimalist models of the rainfall-runoff chain provide estimates of regional climate regimes governing the watersheds of the past, present, or future.

Read: Fraedrich, K., F. Sielmann, D. Cai and X. Zhu (2016): Climate dynamics on watershed scale: along the rainfall-runoff chain. In: The Fluid Dynamcis of Climate, International Centre for Mechanical Sciences (CISM), Springer Verlag. doi: 10.1007/978-3-7091-1893-1_8. Online: link.springer.com/chapter/10.1007/978-3-7091-1893-1_8 Contact: Frank Sielmann (frank.sielmann@uni-hamburg.de)

Date issued:  25. March 2016

Assessing the Capability of a Downscaled Urban Land Surface Temperature Time Series to Reproduce the Spatiotemporal Features of the Original Data

Downscaling of geostationary Land Surface Temperature (LST) data can compensate the lack of high spatiotemporal LST data for urban climate studies. The generated datasets must accurately reproduce the spatiotemporal features of the coarse-scale LST time series with greater spatial detail. This study assesses the accuracy, correct pattern formation and the spatiotemporal inter-relationships of an urban three-month downscaled geostationary LST time series. The results suggest that the downscaling process preserved the radiometry of the original data, reproduced the smooth diurnal cycle but the autocorrelation of the downscaled data was higher than the original coarse-scale data.

Read: Sismanidis, P., I. Keramitsoglou, C. T. Kiranoudis and B. Bechtel (2016): Assessing the Capability of a Downscaled Urban Land Surface Temperature Time Series to Reproduce the Spatiotemporal Features of the Original Data. Remote Sensing, 8:274
Online:
http://www.mdpi.com/2072-4292/8/4/274/htm

Contact: Benjamin Bechtel (benjamin.bechteldummy@uni-hamburgdummy2.de)

 

Date issued:  22. March 2016

Mobile measurement techniques for local and micro-scale studies in urban and topo-climatology

Technical development during the last two decades has brought new potential and new applications for ­mobile measurements. In this paper, we present six case studies where mobile measurement devices were used to acquire data for meteorological and climatological research. Three case studies deal with ground-based mobile measurements – on buses for urban climate measurements and on a vessel on a lake – and three with airborne platforms – on a cable car and on an unmanned aerial vehicle for vertical soundings and on a tethered balloon sonde for cloud physics. One case study was conducted on public transport busses in Hamburg financed by CliSAP.

Read: Seidel, J., G. Ketzler, B. Bechtel, B. Thies, A. Phillipp et al. (2016): New Perspectives in Urban and Topoclimatology using Mobile Measurement Techniques. DIE ERDE, 147, 15-39.
Online:
http://www.die-erde.org/index.php/die-erde/article/view/257

Contact: Benjamin Bechtel (benjamin.bechteldummy@uni-hamburgdummy2.de)

 

Date issued:  18. March 2016

SMOS sea ice product: Operational application and validation in the Barents Sea marginal ice zone

A sea ice forecast system for ship route optimisation has been developed and was tested during a field campaign in the Barents Sea with the ice-strengthened research vessel RV Lance. The ship cruise was complemented with coordinated measurements from a helicopter and the research aircraft Polar 5 to validate sea ice thickness retrieval methods. Ice thicknesses derived from the surface elevation measured by an airborne laser scanner and from simultaneous 1.4 GHz radiometer measurements correlate well up to 1.5 m which is more than previously anticipated.

Read: Kaleschke, L., X. Tian-Kunze, N. Maaß, A. Beitsch, A. Wernecke, M. Miernecki, et al. (2016): SMOS sea ice product: Operational application and validation in the Barents Sea marginal ice zone. Remote Sensing of Environment.
Online:
http://www.sciencedirect.com/science/article/pii/S003442571630102X

 

Date issued:  12. March 2016

Interannual variability of the Arctic freshwater cycle in the second half of the twentieth century in a regionally coupled climate model

We use a regionally coupled ocean-sea ice-atmosphere-hydrological discharge model to investigate the influence of changes in the atmospheric large-scale circulation on the interannual variability of the Arctic freshwater components. We show that few atmospheric winter modes explain large parts of the interannual variability of the freshwater cycle. Not only specific winter conditions but also increased precipitation in late spring and summer, caused by enhanced cyclone activity over land, lead to increased Eurasian runoff, which is responsible for most of the variability in Arctic river runoff.

Read: Niederdrenk, A. L., S. V. Sein and U. Mikolajewicz (2016): Interannual variability of the Arctic freshwater cycle in the second half of the twentieth century in a regionally coupled climate model. Climate Dynamics, 1-18.
Online:
http://link.springer.com/article/10.1007/s00382-016-3047-1

Contact: Laura Niederdrenk (laura.niederdrenkdummy@mpimet.mpgdummy2.de)

 

Date issued:  5. March 2016

Spatial and temporal variability of urban soil water dynamics observed by a soil monitoring network

The spatio-temporal variability and heterogeneity of soil moisture in urban areas and the possible influencing factors are described and quantified, using data of the HUSCO monitoring network in the city of Hamburg, Germany. Soil moisture data from ten observation sites was evaluated for two different years and soil hydrological simulations with SWAP were calculated for a selected site. The temporal evolution of soil water content and tension for the sites was very distinct, related to soil substrate, organic matter content, rooting depth of vegetation and groundwater table depth. While soil properties are mainly determinant for the long-term progression of soil hydrology, local site factors affect the short-term regime. A shallow groundwater table contributes to more constant water dynamics while the relative decrease of water during a dry phase is diminished.

Read: Wiesner, S., A. Gröngröft, F. Ament, A. Eschenbach (2016): Spatial and temporal variability of urban soil water dynamics observed by a soil monitoring network. Journal of Soils and Sediments, (), 1-15. [doi: 10.1007/s11368-016-1385-6]
Online:
http://link.springer.com/article/10.1007/s11368-016-1385-6

Contact: Sarah Wiesner (sarah.wiesner @mpimet.mpg.de)

 

Date issued:  4. March 2016

A study of surface semi-geostrophic turbulence: freely decaying dynamics

In this study we give a characterization of semi-geostrophic turbulence by performing freely decaying simulations for the case of constant uniform potential vorticity, a set of equations known as the surface semi-geostrophic approximation. The equations are formulated as conservation laws for potential temperature and potential vorticity, with a nonlinear Monge–Ampère type inversion equation for the streamfunction, expressed in a transformed coordinate system that follows the geostrophic flow. We perform model studies of turbulent surface semi-geostrophic flows in a domain doubly periodic in the horizontal and limited in the vertical by two rigid lids, allowing for variations of potential temperature at one of the boundaries, and we compare the results with those obtained in the corresponding surface quasi-geostrophic case. The results show that, while the surface quasi-geostrophic dynamics is dominated by a symmetric population of cyclones and anticyclones, the surface semi-geostrophic dynamics features a more prominent role of fronts and filaments. The resulting distribution of potential temperature is strongly skewed and peaked at non-zero values at and close to the active boundary, while symmetry is restored in the interior of the domain, where small-scale frontal structures do not penetrate. In surface semi-geostrophic turbulence, energy spectra are less steep than in the surface quasi-geostrophic case, with more energy concentrated at small scales for increasing Rossby number. The energy related to frontal structures, the lateral strain rate and the vertical velocities are largest close to the active boundary. These results show that the semi-geostrophic model could be of interest for studying the lateral mixing of properties in geophysical flows.

Read: Ragone, F. and G. Badin (2016): Surface semi-geostrophic turbulence: freely-evolving dynamics, Journal of Fluid Mechanics, 792, 740-774
Online:
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10215801&fulltextType=RA&fileId=S0022112016001166

 

Date issued:  2. March 2016

4000 Years of Changing Wetness in a Permafrost Polygon Peatland (Kytalyk, NE Siberia): A Comparative High-Resolution Multi-Proxy Study

This paper presents a 105.5 cm long peat section with a base dating of about 4000 cal yr BP from an ice-wedge polygon mire near Kytalyk (NE Siberia), which was analysed for pollen, macrofossils, testate amoebae, geochemistry and sediment properties in order to compare the suitability of these proxies to reconstruct past surface wetness. We found that the analysed proxies show similar wetness trends. Pollen and geochemistry data did not always permit wetness reconstruction, the former because many pollen types do not allow the inference of taxa at a low taxonomic resolution, the latter because later taphonomic processes modify chemical variables also in deeper peat layers. Macrofossils provided the most detailed wetness reconstruction, because they could be identified to the level of genera or species of which the moisture requirements are accurately known from their present-day distribution in ice-wedge polygons. However, as the proxies sometimes show contradictory results, a multi-proxy approach is preferable over a single proxy interpretation as it allows the reconstruction of environmental development in a broader palaeoecological context.

Read: Teltewskoi, A., F. Beermann, I. Beil, A. Bobrov, P. de Klerk P, S. Lorenz et al. (2016): 4000 years of changing wetness in a permafrost polygon peatland (Kytalyk, NE Siberia): a comparative high resolution multi-proxy study. Permafrost and Periglacial Processes. 27:76–95.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/ppp.1869/full

 

Date issued:  22. February 2016

Testing the validity of productivity proxy indicators in high altitude Tso Moriri Lake, NW Himalaya (India)

Investigations on catchment, vegetation, and lake surface sediments were used to identify end members and reconstruct past lacustrine primary productivity (LPP) in the Tso Moriri Lake. Data reveal limitations of using isotopic and C/N data on bulk organics as indicators of LPP. LPP in recent times is not much higher than during the early Holocene warm period ruling out the possibility of large carbon sequestration in high altitude oligotrophic lakes.

Read: Prasad, S., P. K. Mishra, P. Menzel, B. Gaye, A. Jehangi and A. R. Yousuf (2016):

Testing the validity of productivity proxy indicators in high altitude Tso Moriri Lake, NW Himalaya (India). Palaeogeography, Palaeoclimatology, Palaeoecology 449, 421-430.
Online:
http://www.sciencedirect.com/science/article/pii/S0031018216001012

 

Date issued:  10. February 2016

Understanding carbon trading: Effects of delegating CO2 responsibility on organizations’ trading behavior

The establishment of a carbon market assumes that there is an effective means of transforming price information into technical carbon reduction measures. However, empirical evidence reveals that the links between price information and carbon management strategies are far from obvious. To understand how delegating CO2 responsibility affects CO2 trading behaviour, this paper proposes a neo-institutionalist approach to answering the question of why companies became sellers, buyers or a combination of both during phase I of the European Emissions Trading Scheme (EU ETS). Original data from a survey on companies that participated in this scheme were collected and analysed. The results support the hypothesis that a company that adopts a decoupling strategy is more likely to buy certificates to fulfil their emissions targets. Adopting a coupling strategy indicates that a company is more likely to become a seller, all else equal. Professional identity is the theoretical basis for this relationship. In today’s context, important emitter countries, such as China and Korea, have launched their own emissions markets, copying many aspects of the EU ETS. For the positive development of these markets and as a way of establishing a global emissions market, these new schemes should learn from the EU ETS experience.

Read: Rodriguez Lopez, J.M., A. Engels and L. Knoll (2016): Understanding carbon trading: Effects of delegating CO2 responsibility on organizations’ trading behavior.  Climate Policy (Vol. is forthcoming) DOI: 10.1080/14693062.2015.1119096
Online:
http://www.tandfonline.com/doi/full/10.1080/14693062.2015.1119096

Contact: Miguel Rodriguez Lopez(miguel.rodriguezdummy@uni-hamburgdummy2.de)

 

Date issued:  4. February 2016

Climate change vulnerability, adaptation and risk perceptions at farm level in Punjab, Pakistan

Using cross-sectional data of 450 farm household from three districts in Punjab, Pakistan, this study investigates the farm level risk perceptions and different aspects of vulnerability to climate change including sensitivity and adaptive capacity at farm level in Pakistan.

Read: Abid, M., J. Schilling, J. Scheffran and F. Zulfiqar (2016): Climate change vulnerability, adaptation and risk perceptions at farm level in Punjab, Pakistan. Science of the Total Environment, 547, 447-460.
Online:
http://www.sciencedirect.com/science/article/pii/S0048969715311086

 

Date issued:  19. January 2016

Seasonal and spatial variation in suspended matter, organic carbon, nitrogen, and nutrient concentrations of the Senegal River in West Africa

The Senegal River basin accommodates a very fast growing population of at present 3.5 million inhabitants. It crosses several climate zones from the source in the wet tropics to the river mouth in the Sahel. This paper provides the first data on organic carbon, nitrogen and nutrient concentrations as well as discharges from the three major upstream tributaries to the river mouth.  Anthropogenic impact is low all along the river so that base line data on water quality are provided. Diffusive supplies from the fast growing agriculture lead to elevated nitrate concentrations in the downstream river basin. Our estimates of total suspended matter discharge (TSM) are similar to the only available literature data which are from a period of severe drought in the early 1980s. We propose that the recently observed Sahelian greening could have reduced denudation and thus TSM concentrations.

Read: Mbaye, M.L., A. T. Gaye, A. Spitzy, K. Dähnke, A. Afouda, B. Gaye (2016): Seasonal and spatial variation in suspended matter, organic carbon, nitrogen, and nutrient concentrations of the Senegal River in West Africa. Limnologica - Ecology and Management of Inland Waters 57, 1-13.
Online:
http://www.sciencedirect.com/science/article/pii/S0075951116000049

 

Date issued:  January 2016

Natural and anthropogenic influence on the distribution of salt marsh foraminifera in the Bay of Tümlau, German North Sea

We studied the distribution and ecology of modern foraminifera in a salt marsh in the Bay of Tümlau,Eiderstedt peninsula at the German North Sea coast; this marsh is influenced by human activities. Little information is available on the foraminiferal fauna from such altered ecosystems. Results show that the faunas lack a consistent relation to tide levels, restricting the applicability of foraminiferal reference data sets from human-interfered salt marshes for past sea-level reconstructions.

Read: Müller-Navarra, K., Y. Milker, and G. Schmiedl (2016): NATURAL AND ANTHROPOGENIC INFLUENCE ON THE DISTRIBUTION OF SALT MARSH FORAMINIFERA IN THE BAY OF TÜMLAU, GERMAN NORTH SEA. The Journal of Foraminiferal Research, 46(1), 61-74.
Online:
http://jfr.geoscienceworld.org/content/46/1/61.short

Contact: Katharina Müller-Navarra (katharina.mueller-navarradummy@uni-hamburgdummy2.de)


Date issued: 
17. December 2015

Is climate-smart conservation feasible in Europe? Spatial relations of protected areas, soil carbon, and land values

The expectations on protected areas to deliver not only biodiversity conservation but also to provide an array of different ecosystem services rise. Sequestration and storage of carbon are promising services that protected areas may provide. Our study integrates spatially explicit data on terrestrial Natura 2000 sites, soil organic carbon, and agricultural land values to estimate the potential for climate-smart conservation planning in the European Union. Results suggest that biodiversity protection and mitigation of climate change through conservation of soil carbon could be simultaneously achieved in Europe’s protected areas and beyond.

Read: Jantke, K., J. Müller, N. Trapp and B. Blanz (2016): Is climate-smart conservation feasible in Europe? Spatial relations of protected areas, soil carbon and land values, Environmental Science & Policy, 47, 40-49.
Online:
http://www.sciencedirect.com/science/article/pii/S1462901115301143

 

Date issued:  10. December 2015

Spatio-temporal variance and meteorological drivers of the urban heat island in a European city

Urban areas are especially vulnerable to high temperatures. Thus good knowledge about the local urban climate and simple and robust projection methods are needed. This study has analysed the spatio-temporal variance of the mean nocturnal urban heat island (UHI) of Hamburg, with observations from 40 stations from different suppliers as well as its synoptic meteorological drivers. For the stations with highest UHI intensities, up to 68.7 % of the variance could be explained by seasonal empirical models and even up to 76.6 % by monthly models considering relative humidity, wind speed, cloud cover and objective weathertypes. The response to the meteorological parameters differed between the stations.

Read: Arnd,s D., J. Böhner and B. Bechtel (2016): Spatio-temporal variance and meteorological drivers of the urban heat island in a European city. Theor Appl Climatol:1–19. doi: 10.1007/s00704-015-1687-4
Online: http://link.springer.com/article/10.1007/s00704-015-1687-4

Contact: Benjamin Bechtel (benjamin.bechtel@uni-hamburg.de)

Date issued:  February 2016

Escaping the double bind: from the management of uncertainty towards integrated climate research

How do climate scientists deal with the permanent double bind of maintaining fidelity to scientific standards, while the object of their research is politically charged? After Climategate and other public affairs, the management of uncertainty was one of the strategies to regain public trust. In this article, I critically examine at the example of climate research in Hamburg how concepts like the “honest broker” and “postnormal science” are used to include social sciences into climate research. As a result I conclude that the fuzziness of these concepts does not guarantee a qualitatively different approach; climate change is still primarily considered as a physical phenomenon, while social sciences are mandated to communicate this knowledge and to monitor society. But integrated research is still work in progress and bears the potential to deal in more productive ways with the double bind inherent in climate research.

Read: Krauß, W. (2016): Escaping the double bind: from the management of uncertainty towards integrated climate research. In: Crate, Susan & Mark Nuttall, Anthropology and Climate Change, second edition, chapter 27. Left Coast Press.
Online: accepted

Contact: Werner Krauß (werner.krauss@gmail.com)

***

Date issued:  25 January 2016

Anthropogenic climate change: how to understand the weak links between scientific evidence, public perception, and low-carbon practices

This review article presents an overview of recent literature on: the scientific consensus about the attribution of climate change to anthropogenic sources; successes and failures to create a global policy regime to lower worldwide carbon emissions; recent developments in the public perception of climate change and associated risks; and the persistence of highly carbon-intensive practices in spite of scientific evidence on the attribution of climate change to anthropogenic causes. Holistic approaches to understanding patterns of consumption, focusing on ensembles of social practices, may explain this persistence, however, such approaches are still in their infancy with regard to developing proactive ideas for policies to promote low-carbon practices more effectively.

Read: Engels, A. (2016): Anthropogenic climate change: how to understand the weak links between scientific evidence, public perception, and low-carbon practices. Energy and Emission Control Technologies 2016:4 17–26.
Online:
http://dx.doi.org/10.2147/EECT.S63005http://dx.doi.org/10.2147/EECT.S63005
Contact: Anita Engels (
anita.engels@wiso.uni-hamburg.de)

***

Date issued: 07 January 2016

Sustainable Internationalization? Measuring the Diversity of Internationalization at Higher Education Institutions

Sustainability and internationalization are considered to be core values of Higher Education Institutions (HEIs), but their relationship is rarely investigated. The current study develops a framework to create a sustainable internationalization policy for an HEI; it analyzes how to measure the sustainability of an internationalization policy in two steps. The findings suggest that the distribution of resources for internationalization says more about the sustainable character of an HEI than the absolute amount of invested resources. To evaluate the sustainability of an HEI’s internationalization strategy, it is therefore necessary to look at the distribution of target countries in addition to the mere absolute level of funding.

Read: Lopez, M. R., B. R. K. Runkle, S. Roski, J. Stöver, K.  Jantke, M. Gottschick and D. Rothe (2016): Sustainable Internationalization? Measuring the Diversity of Internationalization at Higher Education Institutions. In The Contribution of Social Sciences to Sustainable Development at Universities (pp. 21-37). Springer International Publishing. DOI: 10.1007/978-3-319-26866-8_2.
Online:
http://link.springer.com/chapter/10.1007%2F978-3-319-26866-8_2http://link.springer.com/chapter/10.1007%2F978-3-319-26866-8_2
Contact: Juan Miguel Rodriguez Lopez (
miguel.rodriguez@uni-hamburg.de)

***

Date issued:  25 December 2015

An Experimental and Numerical Study of Long Wave Run-Up on a Plane Beach

This research is to facilitate the current understanding of long wave dynamics at coasts and during on-land propagation; experimental and numerical approaches are compared against existing analytical expressions for the long wave run-up. Leading depression sinusoidal waves are chosen to model these dynamics. The experimental study was conducted using a new pump-driven wave generator and the numerical experiments were carried out with a one-dimensional discontinuous Galerkin non-linear shallow water model. The numerical model is able to accurately reproduce the run-up elevation and velocities predicted by the theoretical expressions. Depending on the surf similarity of the generated waves and due to imperfections of the experimental wave generation, riding waves are observed in the experimental results. These artifacts can also be confirmed in the numerical study when the data from the physical experiments is assimilated. Qualitatively, scale effects associated with the experimental setting are discussed. Finally, shoreline velocities, run-up and run-down are determined and shown to largely agree with analytical predictions.

Read: Drähne, U., N. Goseberg, S. Vater, N. Beisiegel and J. Behrens (2015): An Experimental and Numerical Study of Long Wave Run-Up on a Plane Beach. Journal of Marine Science and Engineering, 2016, Vol. 4, Issue 1, p. 1, doi: 10.3390/jmse4010001
Online:
http://www.mdpi.com/2077-1312/4/1/1/htm
Contact: Stefan Vater (stefan.vater@uni-hamburg.de)

***

Date issued:  18 December 2015

Satellite and Ground Based Thermal Observation of the 2014 Effusive Eruption at Stromboli Volcano

This paper presents the first long term satellite monitoring  by the small satellite DLR's Technology Experiment Carrier-1 (TET-1). Using the radiant density approach, TET-1 data were used to calibrate the MODVOLC data and estimate the time averaged lava discharge rate. With a mean output rate of 0.87 m³/s during the three-month-long eruption, we estimate the total erupted volume to be 7.4 × 106 m³.

Read: Zakšek, K., M. Hort, and E. Lorenz (2015): Satellite and Ground Based Thermal Observation of the 2014 Effusive Eruption at Stromboli Volcano. Remote Sens. 2015, 7, 17190-17211.
Online:
http://www.mdpi.com/2072-4292/7/12/15876
Contact: Klemen Zakšek (klemen.zaksek@uni-hamburg.de)

***

Date issued: 17 December 2015

ESA's Soil Moisture and Ocean Salinity mission: From science to operational applications

The Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, is the European Space Agency's (ESA) second Earth Explorer Opportunity mission. The scientific objectives of the SMOS mission directly respond to the need for global observations of soil moisture and ocean salinity, two key variables used in predictive hydrological, oceanographic and atmospheric models. For the extension phase a new mission objective has been added, namely that daily sea ice thickness estimates based on SMOS observations.

Read: Mecklenburg S., M. Drusch, L. Kaleschke, N. Rodriguez-Fernandez and  N. Reul et al. (2015): ESA's soil moisture and ocean salinity mission: Mission performance and operations. Geoscience and Remote Sensing, IEEE Transactions on, 50(5), 1354-1366.
Online: http://www.sciencedirect.com/science/article/pii/S0034425715302467
Contact: Lars Kaleschke (
lars.kaleschke@uni-hamburg.de)

***

Date issued:  15 December 2015

ESG and financial performance: aggregated evidence from more than 2000 empirical studies

The search for a relation between environmental, social, and governance (ESG) criteria and corporate financial performance (CFP) can be traced back to the beginning of the 1970s. Scholars and investors have published more than 2000 empirical studies and several review studies on this relation since then. The largest previous review study analyzes just a fraction of existing primary studies, making findings difficult to generalize. Thus, knowledge on the financial effects of ESG criteria remains fragmented. To overcome this shortcoming, this study extracts all provided primary and secondary data of previous academic review studies. Through doing this, the study combines the findings of about 2200 individual studies. Hence, this study is by far the most exhaustive overview of academic research on this topic and allows for generalizable statements. The results show that the business case for ESG investing is empirically very well founded. Roughly 90% of studies find a nonnegative ESG–CFP relation. More importantly, the large majority of studies reports positive findings. We highlight that the positive ESG impact on CFP appears stable over time. Promising results are obtained when differentiating for portfolio and nonportfolio studies, regions, and young asset classes for ESG investing such as emerging markets, corporate bonds, and green real estate.

Read: Friede, G.,T. Busch and A. Bassen (2015): ESG and financial performance: aggregated evidence from more than 2000 empirical studies. In: Journal of Sustainable Finance & Investment, 5(4), 210-233.
Online:
http://www.tandfonline.com/doi/abs/10.1080/20430795.2015.1118917
Contact: Alexander Bassen (alexander.bassen@wiso.uni-hamburg.de)

***

Date issued: 9 December 2015

Regulation of methane production, oxidation and emission by vascular plants and bryophytes in ponds of the northeast Siberian polygonal tundra

Impact of vegetation on methane fluxes from wetlands of the Siberian tundra
The paper report the first methane fluxes from small ponds of the Siberian polygonal tundra. Vascular plants increase methane fluxes by fuelling methanogenesis and channelling methane into the atmosphere. In contrast, submerged living mosses provide oxygen below the water table, speeding up methane oxidation. Most of the produced methane was oxidized below the water table of the ponds, a process still neglected in most biogeochemical models.

Read: Knoblauch, C., O. Spott, S. Evgrafova, L. Kutzbach, and E.-M. Pfeiffer (2015): Regulation of methane production, oxidation and emission by vascular plants and bryophytes in ponds of the northeast Siberian polygonal tundra. In: Journal of Geophysical Research: Biogeosciences, 120, 2525–2541,doi: 10.1002/2015JG003053.
Online: http://onlinelibrary.wiley.com/doi/10.1002/2015JG003053/full
Contact: Christian Knoblauch
(christian.knoblauch@uni-hamburg.de)

***

Date issued:  27 November 2015

Weibull wind-speed distribution parameters derived from a combination of wind-lidar and tall-mast measurements over land, coastal and marine sites

Wind-speed observations from tall towers are used in combination with observations up to 600 m in altitude from a Doppler wind lidar to study the long-term wind conditions over suburban (Hamburg), rural coastal (Høvsøre) and marine (FINO3) sites. The variability in the wind conditions among the sites is expressed in terms of mean wind speed and Weibull distribution shape-parameter profiles. The consequences of the carrier-to-noise-ratio (CNR) threshold-value choice on the wind-lidar observations are revealed as follows. When the wind-lidar CNR is lower than a prescribed threshold value, the observations are often filtered out as the uncertainty in the wind-speed measurements increases. For a pulsed heterodyne Doppler lidar, use of the traditional -22 dB CNR threshold value at all measuring levels up to 600 m results in a » 7% overestimation of the long-term mean wind speed over land, and a » 12% overestimation in coastal and marine environments. In addition, the height of the profile maximum of the shape parameter of the Weibull distribution (so-called reversal height) is found to depend on the applied CNR threshold; it is found to be lower at small CNR threshold values.The reversal height is greater in the suburban (high roughness) than in the rural (low roughness) area. In coastal areas the reversal height is lower than that over land and relates to the internal boundary layer that develops downwind from the coastline. Over the sea the shape parameter increases towards the sea surface. A parametrization of the vertical profile of the shape parameter fits well observations over land, coastal regions and over the sea. An applied model for the dependence of the reversal height on the surface roughness is in good agreement with the observations over land.

Read: Gryning, S.E., R. Floors, A. Pena, E. Batchvarova, and B. Brümmer (2015): Weibull wind-speed distribution parameters derived from a combination of wind-lidar and tall-mast measurements over land, coastal and marine sites. Boundary-Layer Meteorol., DOI: 10.1007/s10546-015-0113-x.
Online:
http://link.springer.com/article/10.1007/s10546-015-0113-x
Contact: Burghard Brümmer (burghard.bruemmer@uni-hamburg.de)

***

Date issued:  17 November 2015

Changes in surface solar radiation in Northeastern Spain over the past six centuries recorded by tree-ring δ13C

Although solar radiation at the surface plays a determinant role in carbon discrimination in tree rings, stable carbon isotope chronologies (δ13C) have often been interpreted as a temperature proxy due to the co-variability of temperature and surface solar radiation. Furthermore, even when surface solar radiation is assumed to be the main driver of 13C discrimination in tree rings, δ13C records have been calibrated against sunshine duration or cloud cover series for which longer observational records exists. In this study, we use different instrumental and satellite data over northeast Spain (southern Europe) to identify the main driver of tree-ring 13C discrimination in this region. Special attention is paid to periods in which the co-variability of those climate variables may have been weaker, such as years after large volcanic eruptions. The analysis identified surface solar radiation as the main driver of tree-ring δ13C changes in this region, although the influence of other climatic factors may not be negligible. Accordingly, we suggest that a reconstruction of SSR over the last 600 years is possible. The relation between multidecadal variations of an independent temperature reconstruction and surface solar radiation in this region shows no clear sign, and warmer (colder) periods may be accompanied by both higher and lower surface solar radiation. However, our reconstructed records of surface solar radiation reveals a sunnier Little Ice Age in agreement with other δ13C tree-ring series used to reconstruct sunshine duration in central and northern Europe.

Read: Dorado-Liñán, I., A. Sanchez-Lorenzo, E. G. Merino, O. Planells, I. Heinrich, G. Helle, and E. Zorita (2015): Changes in surface solar radiation in Northeastern Spain over the past six centuries recorded by tree-ring δ13C. Climate Dynamics, 1-14.
Online:
http://link.springer.com/article/10.1007/s00382-015-2881-x
Contact: Eduardo Zorita (eduardo.zorita@hzg.de)

***

Date issued:  15 November 2015

Rezension: Die Entstehung der grünen Politik. Kultursoziologie der westdeutschen Umweltbewegung

Grüne Politik ist heute längst in der Mitte der Gesellschaft angekommen. Doch wie ist es dazu gekommen, wo liegen die Ursprünge und die Ursachen für diesen rasanten Aufstieg, der längst auch die großen Parteien erfasst hat? Für den Soziologen Andreas Pettenkofer handelt es sich dabei um eine unwahrscheinliche Entwicklung, die weder mit Theorien rationalen Handelns noch mit der systemischen Notwendigkeit im Modernisierungsprozess allein erklärt werden kann.

Read: Krauß, W. (2015): Rezension von: Andreas Pettenkofer: Die Entstehung der grünen Politik. Kultursoziologie der westdeutschen Umweltbewegung, Frankfurt/M.: Campus 2014, in: sehepunkte 15, Nr. 11.
Online:
http://www.sehepunkte.de/2015/11/21019.html
Contact: Werner Krauß (werner.krauss@gmail.com)

***

Date issued:  31. October 2015

Anomalous hydrographic conditions in the western Barents Sea observed in March 2014

Observational data have been collected during a cruise to the western Barents Sea in March 2014 covering 33 stations along three west–east sections at 76.34°N, 77.26°N and 78.49°N and along one south–north section at 19.47°E. Our observations suggest a wedge-like water masses structure with colder and fresher Arctic Water moving southward, gliding over warmer and more saline Atlantic Water which below the surface moves to the north. Atlantic Water in the Storfjorden Trench reached farther north than 76.5°N and was present on the eastern and western slopes of the Spitsbergen Bank. Our measurements indicate limited dense water formation in the Storfjorden. A comparison with historical data over the years 1923–2011 reveal an anomalous northern location of the Polar Front for this time of the year in March 2014. A point by point comparison with ten historical stations in 1983 and 1986 shows significantly warmer (by up to 3.8 °C) and saltier (by up to 2.49 psu) conditions in 2014 for nine out of ten stations. Moreover, stations dominated by the Atlantic inflow experienced the largest changes, whereas in stations located in the area of the Arctic outflow the changes were smallest. Furthermore, we used satellite and decadal reanalysis data to estimate the climate variability defined by a range of two standard deviations. We found that in the Storfjorden Trench in March 2014 the water transport was within the range, while the water temperature exceeded the upper limit of climate variability. The sea ice extent in the western Barents Sea was below the lower limit of climate variability from mid-February to mid-March 2014. Combining in situ, satellite and model data, we were able to attribute the warm anomaly observed in March 2014 to two main reasons: (1) an increase of Atlantic water temperature which was evident already in the beginning of 2014 and (2) very little cooling in February and March 2014. From these results we conclude that the north-western Barents Sea is a key region to monitor local response on climate change signals in the Arctic Ocean.

Read: Dobrynin, M. and T. Pohlmann (2015): Anomalous hydrographic conditions in the western Barents Sea observed in March 2014. Continental Shelf Research, doi:10.1016/j.csr.2015.10.020
Online:
http://www.sciencedirect.com/science/article/pii/S0278434315300959http://www.sciencedirect.com/science/article/pii/S0278434315300959

Contact: Mikhail Dobrynin (mikhail.dobrynindummy@uni-hamburgdummy2.demikhail.dobrynindummy@uni-hamburgdummy2.de)

***

Date issued: 15. October 2015

Lead detection in Arctic sea ice from CryoSat-2: quality assessment, lead area fraction and width distribution

Leads in Arctic sea ice have a dominant effect on the exchange between the ocean and the atmosphere. Visual MODIS scenes are used to validate and improve the detection of leads from altimeter measurements of the satellite CryoSat-2. The rarely used maximum power of the returning signal shows the best classification properties. Lead area fraction and width distribution estimates based on CryoSat-2 complement other studies and deepen our understanding of lead characteristics. Lead area fraction maps can be accessed directly via the ICDC.

Read: Wernecke, A. and L. Kaleschke (2015): Lead detection in Arctic sea ice from CryoSat-2: quality assessment, lead area fraction and width distribution, The Cryosphere, 9, 1955-1968, doi:10.5194/tc-9-1955-2015

 Online: http://www.the-cryosphere.net/9/1955/2015/tc-9-1955-2015.html

Contact: Andreas Wernecke (andreas.werneckedummy@uni-hamburgdummy2.deandreas.werneckedummy@uni-hamburgdummy2.de)

***

Date issued: 5. October 2015

Securitization of Media Reporting on Climate Change? A Cross-national Analysis in Nine Countries, Security Dialogue

Security implications of climate change have been highlighted by various political and advisory bodies, as well as non-governmental organizations (NGOs), in recent years. It is unclear, however, whether such a ‘securitization’ of climate change can also be found beyond institutionalized politics in the public realm, and beyond Western countries. This article addresses these questions by investigating mass media coverage in nine countries over a period of 15 years. Based on an analysis of more than 101,000 newspaper articles, it shows an increasing discussion of climate change in security terms, with diverging trends in the analysed countries. While Western, industrialized countries such as the USA, the UK or Australia display an increasing securitization of climate change, the amount of securitizing language has decreased in India and South Africa. Moreover, different countries refer to different security dimensions – with regard both to the subjects whose security is of concern (national security, human security) and to the type of resources that are discussed in security terms (energy security, water security, food security). While Western countries strongly focus on national security and energy security, emerging economies place greater emphasis on food and, less pronounced, on water security.

Read: Schäfer, M. S., J. Scheffran and L. Penniket (2015): Securitization of Media Reporting on Climate Change? A Cross-national Analysis in Nine Countries, Security Dialogue, doi:10.1177/0967010615600915

Online: http://sdi.sagepub.com/content/early/2015/10/05/0967010615600915.abstract

Contact: Jürgen Scheffran (juergen.scheffrandummy@uni-hamburgdummy2.de)

***

Date issued: 1. October 2015

Pulsed Vulcanian explosions: A characterization of eruption dynamics using Doppler radar

To date the prediction of volcanic ash transport and dispersion is based on numerical models, which use input from the so-called classic buoyant plume theory that assumes a steady ejection of volcanic ejecta. In our article, we analyse the temporal variability of volcanic ejecta velocities measured by a Doppler radar at two dome building volcanoes - Volcán de Colima in Mexico and Santiaguito volcanic complex in Guatemala. The measured trends suggest that the Vulcanian eruptions at both volcanoes consist of individual explosions or pulses that follow each other with gaps of 2-5 seconds. This means that the ejection of volcanic particles into the atmosphere is by no means a steady or constant process.

Read: Scharff, L., M. Hort,and N. R. Varley (2015): Pulsed Vulcanian explosions: A characterization of eruption dynamics using Doppler radar, Geology, 2015, 43, 995-998, doi: 10.1130/G36705.1

Online: http://geology.geoscienceworld.org/cgi/content/full/43/11/995

Contact: Lea Scharff (lea.scharffdummy@uni-hamburgdummy2.de)

***

Date issued: September 2015

Disabling the Steering Wheel? National and International Actors' Climate Change Mitigation Strategies in Latin America

This article addresses the question of how Brazil, Costa Rica, and Colombia came to decide on their climate change mitigation strategies, which are based on market‐oriented policies. The analysis compares Brazilian bioethanol, Costa Rican renewable energy, and Colombia's clean development mechanism. Using the "chicken game," the best response is to "disable the steering wheel." This means that an actor reduces his or her capacity for action in order to signal a commitment to continue acting in line with his or her past behaviour. The study assesses this strategy at the level of relationships between national and international actors. The findings show that the national actors examined here are either continuing with criticised projects, in the Brazilian case, or slowing down their mitigating strategies, in the cases of Costa Rica and Colombia, and thereby restricting their capacity for action in order to reach a better negotiating position.

Read: Rodriguez Lopez, M., D. Vieira do Nascimento, D. Garcia Sanche and M. Bolivar Lobato (2015): Disabling the Steering Wheel? National and International Actors' Climate Change Mitigation Strategies in Latin America. GIGA Working Paper, No. 278

Online: https://www.giga-hamburg.de/de/publication/disabling-the-steering-wheel-national-and-international-actors-climate-change-mitigationhttps://www.giga-hamburg.de/de/publication/disabling-the-steering-wheel-national-and-international-actors-climate-change-mitigation

Contact: Miguel Rodriguez Lopez (miguel.rodriguezdummy@uni-hamburgdummy2.demiguel.rodriguezdummy@uni-hamburgdummy2.de )

***

Date issued: September 2015

Remote Sensing of Sustainable Rural-Urban Land Use in Mexico City: A Qualitative Analysis for Reliability and Validity

Mexico City is one of the largest cities on the globe and a site where important transformations of nature reserves into urban areas have been taking place. This paper compared the southern part of Mexico City based on free images available (Landsat – 30m) and high-resolution imagery (RapidEye – 5m) from an explorative qualitative perspective in the logic of reliability and validity. We argue that the resolution of the free imagery available for the assessment of urban development on the structural level of land use is not sufficient to identify the development of specific parts of the city. Despite the fact that the general pattern of changes in land use is observable, changes within the urban structure are difficult to see with a resolution of 30 meters per pixel in the Landsat images. For validity, this analysis is merely graphic, and it shows a promising matching of urban development with environmental and land complaints, nevertheless, a numerical analysis is needed in the future.

Read:  Rodríguez López, J.M., P. Rosso, J. Scheffran and G. C. Delgado Ramos (2015): Remote Sensing of Sustainable Rural-Urban Land Use in Mexico City: A Qualitative Analysis for Reliability and Validity.  Interdisciplina  Vol 3, No 7

Online: http://revistas.unam.mx/index.php/inter/article/view/52413http://revistas.unam.mx/index.php/inter/article/view/52413

Contact: Miguel Rodriguez Lopez (miguel.rodriguezdummy@uni-hamburgdummy2.demiguel.rodriguezdummy@uni-hamburgdummy2.de )

***

Date issued: 21. August 2015

Ash iron mobilization through physicochemical processing in volcanic eruption plumes: a numerical modeling approach

It has been shown that volcanic ash fertilizes the Fe-limited areas of the surface ocean through releasing soluble iron. As ash iron is mostly insoluble upon the eruption, it is hypothesized that heterogeneous in-plume and in-cloud processing of the ash promote the iron solubilization. Direct evidences concerning such processes are, however, lacking. In this study, a 1-D numerical model is developed to simulate the physicochemical interactions of the gas–ash–aerosol in volcanic eruption plumes focusing on the iron mobilization processes at temperatures between 600 and 0 °C. Results show that sulfuric acid and water vapor condense at ~ 150 and ~ 50 °C on the ash surface, respectively. This liquid phase then efficiently scavenges the surrounding gases (> 95 % of HCl, 3–20 % of SO2 and 12–62 % of HF) forming an extremely acidic coating at the ash surface. The low pH conditions of the aqueous film promote acid-mediated dissolution of the Fe-bearing phases present in the ash material. We estimate that 0.1–33 % of the total iron available at the ash surface is dissolved in the aqueous phase before the freezing point is reached. The efficiency of dissolution is controlled by the halogen content of the erupted gas as well as the mineralogy of the iron at ash surface: elevated halogen concentrations and presence of Fe2+-carrying phases lead to the highest dissolution efficiency. Findings of this study are in agreement with the data obtained through leaching experiments.

Read: Hoshyaripour, G. A., M. Hort, and B. Langmann (2015): Ash iron mobilization through physicochemical processing in volcanic eruption plumes: a numerical modeling approach, Atmos. Chem. Phys., 15, 9361-9379, doi:10.5194/acp-15-9361-2015

Online: http://www.atmos-chem-phys.net/15/9361/2015/acp-15-9361-2015.htmlhttp://www.atmos-chem-phys.net/15/9361/2015/acp-15-9361-2015.html

Contact: Matthias Hort (matthias.hortdummy@uni-hamburgdummy2.dematthias.hortdummy@uni-hamburgdummy2.de)

***

Date issued: 20. August 2015, In Press

Strombolian surface activity regimes at Yasur volcano, Vanuatu, as observed by Doppler radar, infrared camera and infrasound

In late 2008 we recorded a continuous multi-parameter data set including Doppler radar, infrared and infrasound data at Yasur volcano, Vanuatu. Our recordings cover a transition in explosive style from ash-rich to ash-free explosions followed again by a phase of high ash discharge. To assess the present paradigm of Strombolian behavior in this study we investigate the geophysical signature of these different explosive episodes and compare our results to observations at Stromboli volcano, Italy. To this end we characterize Yasur's surface activity in terms of material movement, temperature and excess pressure. The joint temporal trend in these data reveals smooth variations of surface activity and regime-like persistence of individual explosion forms over days. Analysis of all data types shows ash-free and ash-rich explosive styles similar to those found at Stromboli volcano. During ash-free activity low echo powers, high explosion velocities and high temperatures result from the movement of isolated hot ballistic clasts. In contrast, ash-rich episodes exhibit high echo powers, low explosion velocities and low temperatures linked to the presence of colder ash-rich plumes. Furthermore ash-free explosions cause high excess pressure signals exhibiting high frequencies opposed to low-amplitude, low-frequency signals accompanying ash-rich activity. To corroborate these findings we compare fifteen representative explosions of each explosive episode. Explosion onset velocities derived from Doppler radar and infrared camera data are in excellent agreement and consistent with overall observations in each regime. Examination of infrasound recordings likewise confirms our observations, although a weak coupling between explosion velocity and excess pressure indicates changes in wave propagation. The overall trend in explosion velocity and excess pressure however demonstrates a general correlation between explosive style and explosion intensity, and points to stability of the uppermost conduit on timescales shorter than at Stromboli volcano.

Read: Meier, K., M. Hort, J. Wassermann and E. Garaebiti (2015): Strombolian surface activity regimes at Yasur volcano, Vanuatu, as observed by Doppler radar, infrared camera and infrasound, J. Volcanol. Geotherm. Res., http://dx.doi.org/10.1016/j.jvolgeores.2015.07.038http://dx.doi.org/10.1016/j.jvolgeores.2015.07.038

Online: http://www.sciencedirect.com/science/article/pii/S0377027315002553http://www.sciencedirect.com/science/article/pii/S0377027315002553

Contact: Matthias Hort (matthias.hortdummy@uni-hamburgdummy2.dematthias.hortdummy@uni-hamburgdummy2.de)

***

Date issued: 03. August 2015

Institutions put to the test: Community-based water management in Namibia during a drought

In Namibia, rural water governance has changed profoundly during the last two decades. When the rains failed in 2012–14, the mobility of people and herds increased and put the newly formed institutional regimes to a critical test. Based on long-term ethnographic fieldwork in seven communities, we examine whether and how management regimes were either altered or applied. The results indicate that cultural models of kinship and reciprocity took priority over formal agreements during the drought.

Read: Schnegg, M. and M. Bollig (2016): Institutions put to the test: Community-based water management in Namibia during a drought, Journal of Arid Environments, Volume 124, Pages 62-71, ISSN 0140-1963, http://dx.doi.org/10.1016/j.jaridenv.2015.07.009.

Online: http://www.sciencedirect.com/science/article/pii/S0140196315300185

Contact: Michael Schnegg (michael.schnegg@uni-hamburg.de)

Date issued:  17. September 2015

Kinematics of large terrestrial impact crater formation inferred from structural analysis and three-dimensional block modeling of the Vredefort Dome, South Africa

The configuration of prominent concentric and radial faults inferred from 3D block modelling supports the hypothesis that the Vredefort Dome formed by centripetal rock movement followed by radial spreading of uplifted rocks. Centripetal rock movement led to the formation of radially disposed transpression zones, whereby distorted supracrustal strata are characterized by a remarkable structural continuity during central uplift formation. This continuity points to a rather strong mechanical coherence of strata throughout the process.

Read: Jahn, A. and U. Riller, (2015): Kinematics of large terrestrial impact crater formation inferred from structural analysis and three-dimensional block modeling of the Vredefort Dome, South Africa, in Osinski, G.R., and Kring, D.A., eds., Large Meteorite Impacts and Planetary Evolution V: Geological Society of America Special Paper 518, SPE518-05, doi:10.1130/2015.2518(05)
Online: specialpapers.gsapubs.org/content/early/2015/09/17/2015.2518_05.abstract
Contact: Ulrich Riller (
ulrich.rillerdummy@uni-hamburgdummy2.de)

***

Date issued:  15. September 2015

Submarine explosive volcanism in the southeastern Terceira Rift/São Miguel region (Azores)

Morphologic studies with sonar data and in situ observations of modern eruptions have revealed some information suggesting how submarine volcanic cones develop, but the information only addresses the modern surfaces of these features.  Here, we describe a study combining morphological data with high-resolution seismic reflection data collected over cones within the southeastern Terceira Rift - a succession of deep basins, volcanic bathymetric highs and islands (e.g. São Miguel) representing the westernmost part of the Eurasian-Nubian plate boundary.

Read: Weiß, B.J., C. Hübscher, D. Wolf, and T. Lüdmann, (2015): Submarine explosive volcanism in the southeastern Terceira Rift/São Miguel region (Azores). J. Volcanol. Geotherm. Res. 303, 79-91, doi: 10.1016/j.jvolgeores.2015.07.028.
Online: www.sciencedirect.com/science/article/pii/S037702731500236X
Contact: Benedikt Weiß (
benedikt.weissdummy@uni-hamburgdummy2.de)

***

Date issued:  10. September 2015

Predictability of threshold exceedances in dynamical systems

In the paper I was assessing the data-driven predictability of extreme events, which are defined as exceedances of some high threshold levels by a scalar observable. The skill of the categoric prediction of such binary events is measured by a quantity that takes into account both true positives and false negatives. The findings suggest that it is a robust but not necessarily universal feature that stronger events are better predictable in dynamical systems. It is also demonstrated that the predictability quantified by some other measure, such as the finite-time maximal Lyapunov exponent, leads to a different conclusion.

Read: Bodai, T. (2015): Predictability of threshold exceedances in dynamical systems, Physica D, dx.doi.org/10.1016/j.physd.2015.08.007
Online: www.sciencedirect.com/science/article/pii/S0167278915001608
Contact: Tamas Bodai (
tamas.bodaidummy@uni-hamburgdummy2.de)

***

Date issued:  09. September 2015

Quasi-nodal third-order Bernstein polynomials in a discontinuous Galerkin model for flooding and drying

In the paper we show how monotone third-order Bernstein polynomials can be used to model the fluid height and momentum in a discontinuous Galerkin inundation model. In contrast to commonly used Lagrange polynomials, these new basis functions prevent unphysically negative values of the fluid height on non-interpolation points thus allowing the use of robust node-based slope limiters and rendering additional filtering on inner-element quadrature points redundant. Standard analytical test cases show an expected improvement of convergence compared to second-order elements.

Read: Beisiegel, N., and J. Behrens, (2015): Quasi-nodal third-order Bernstein polynomials in a discontinuous Galerkin model for flooding and drying. Environmental Earth Sciences, 1-10.
Online: link.springer.com/article/10.1007/s12665-015-4745-4
Contact: Nicole Beisiegel (
nicole.beisiegeldummy@uni-hamburgdummy2.de)

***

Date issued:  02. September 2015

Mapping tree density at a global scale

The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.

Read: Crowther, T. W., H. B. Glick, K. R. Covey, C. Bettigole, D. S. Maynard, S. M. Thomas, ..., P. Borchardt, … & M. A. Bradford, (2015): Mapping tree density at a global scale. Nature, 525(7568), 201-205.
Online: www.nature.com/nature/journal/v525/n7568/abs/nature14967.html
Contact: Peter Borchardt (
peter.borchardtdummy@uni-hamburgdummy2.de)

***

Date issued:  September 2015

Remote Sensing of Sustainable Rural-Urban Land Use in Mexico City: A Qualitative Analysis for Reliability and Validity

Mexico City is one of the largest cities on the globe and a site where important transformations of nature reserves into urban areas have been taking place. This paper compared the southern part of Mexico City based on free images available (Landsat – 30m) and high-resolution imagery (RapidEye – 5m) from an explorative qualitative perspective in the logic of reliability and validity. We argue that the resolution of the free imagery available for the assessment of urban development on the structural level of land use is not sufficient to identify the development of specific parts of the city. Despite the fact that the general pattern of changes in land use is observable, changes within the urban structure are difficult to see with a resolution of 30 meters per pixel in the Landsat images. For validity, this analysis is merely graphic, and it shows a promising matching of urban development with environmental and land complaints, nevertheless, a numerical analysis is needed in the future.

Read: Rodríguez López, J. M., P. Rosso, J. Scheffran and G. C. Delgado Ramos, (2015): Remote Sensing of Sustainable Rural-Urban Land Use in Mexico City: A Qualitative Analysis for Reliability and Validity.  Interdisciplina  Vol 3, No 7.
Online: revistas.unam.mx/index.php/inter/article/view/52413
Contact: Miguel Rodriguez Lopez (
miguel.rodriguezdummy@uni-hamburgdummy2.de)

***

Date issued:  September 2015

Disabling the Steering Wheel? National and International Actors' Climate Change Mitigation Strategies in Latin America

This article addresses the question of how Brazil, Costa Rica, and Colombia came to decide on their climate change mitigation strategies, which are based on market‐oriented policies. The analysis compares Brazilian bioethanol, Costa Rican renewable energy, and Colombia's clean development mechanism. Using the "chicken game," the best response is to "disable the steering wheel." This means that an actor reduces his or her capacity for action in order to signal a commitment to continue acting in line with his or her past behaviour. The study assesses this strategy at the level of relationships between national and international actors. The findings show that the national actors examined here are either continuing with criticised projects, in the Brazilian case, or slowing down their mitigating strategies, in the cases of Costa Rica and Colombia, and thereby restricting their capacity for action in order to reach a better negotiating position.

Read: Rodriguez Lopez, M., D. Vieira do Nascimento, D. Garcia Sanchez and  M. Bolivar Lobato, (2015): Disabling the Steering Wheel? National and International Actors' Climate Change Mitigation Strategies in Latin America. GIGA Working Paper, No. 278
Online: www.giga-hamburg.de/de/publication/disabling-the-steering-wheel-national-and-international-actors-climate-change-mitigation
Contact: Miguel Rodriguez Lopez (
miguel.rodriguezdummy@uni-hamburgdummy2.de)

***

Date issued:  September 2015

Adaptability of backcasting for sustainable development: a case study from Nepal.

Transition management and backcasting are two methodologies that have been developed mainly in the Netherlands to contribute to a transition towards sustainable behavior. In this paper we examine whether these methodologies are also applicable in a developing country using a case study in a small village in the mid-hills of Nepal. Moreover we analyze which adjustments and changes are needed to achieve good results and process quality. First results show that this methodology seems to be appropriate to trigger a change in thinking towards long-term considerations amongst the small scale farmers. Long-range thinking and future envisioning can stimulate investments in technologies that tend to be sustainable and guarantee a safer and more stable return in the long run.

Read: Wieners, E., M. Neuburger, and U. Schickhoff, (2015): Adaptability of backcasting for sustainable development: a case study from Nepal. International Journal of Asian Business and Information Management 6(3):16-27.
Online: www.igi-global.com/article/adaptability-of-backcasting-for-sustainable-development/127626
Contact: Udo Schickhoff (
udo.schickhoffdummy@uni-hamburgdummy2.de)

***

Date issued:  September 2015

Predictive Skill for Regional Interannual Steric Sea Level and Mechanisms for Predictability

Based on decadal hindcasts initialized every five years over the period 1960–2000, the predictive skill of annual-mean regional steric sea level and associated mechanisms are investigated. Predictive skill for steric sea level is found over large areas of the World Ocean, notably over the subtropical Atlantic and Pacific Oceans, along the path of the North Atlantic Current, and over the Indian and Southern Oceans. Mechanisms for the predictability of the thermosteric and halosteric contributions to the steric signal are studied by separating these components into signals originating from processes within and beneath the mixed layer. Contributions originating from below the mixed layer are further decomposed into density-related (isopycnal motion term) and density-compensated (spice term) changes. In regions of the subtropical Pacific and Atlantic Oceans, predictive skill results from the interannual variability associated with the contribution from isopycnal motion to thermosteric sea level. Skill related to thermosteric mixed layer processes is found to be important in the subtropical Atlantic, while the spice contribution shows skill over the subpolar North Atlantic. In the subtropics, the high predictive skill can be rationalized in terms of westward-propagating baroclinic Rossby waves for a lead time of 2–5 yr, as demonstrated using an initialized Rossby wave model. Because of the low Rossby wave speed in high latitudes, this process is not separable from the persistence there.

Read: Polkova, I., A. Köhl, and D. Stammer, (2015): Predictive Skill for Regional Interannual Steric Sea Level and Mechanisms for Predictability. J. Climate, 28, 7407–7419.
doi: dx.doi.org/10.1175/JCLI-D-14-00811.1
Online: journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00811.1
Contact: Iuliia Polkova (
iuliia.polkovadummy@uni-hamburgdummy2.de)

***

Date issued:  20. August 2015

A limiter-based well-balanced discontinuous Galerkin method for shallow-water flows with wetting and drying: One-dimensional case

An important part in the numerical simulation of tsunami and storm surge events is the accurate modeling of flooding and the appearance of dry areas when the water recedes. This paper proposes a new algorithm to model inundation events with piecewise linear Runge–Kutta discontinuous Galerkin approximations applied to the shallow water equations. The main feature is a velocity based "limiting" of the momentum distribution in each cell, which prevents instabilities in case of wetting or drying situations. The proposed wetting and drying treatment is verified with several test cases.

Read: Vater, S., N. Beisiegel, and J. Behrens, (2015): A limiter-based well-balanced discontinuous Galerkin method for shallow-water flows with wetting and drying: One-dimensional case. Advances in Water Resources. Volume 85, Pages 1-13, doi: 10.1016/j.advwatres.2015.08.008.
Online: www.sciencedirect.com/science/article/pii/S0309170815001943
Contact: Stefan Vater (stefan.vaterdummy@uni-hamburgdummy2.de)

***

Date issued:  02. August 2015

Limitations and opportunities of social capital for adaptation to climate change: a case study on the Isles of Scilly

Small islands are among regions most affected by the impacts of global climate change. They are regarded as particularly vulnerable, but from a different point of view, island societies also feature a particular sociocultural resilience, which distinguishes them from continental societies. How do social structures increase the adaptive capacity of small islands towards sea-level rise? I consider the concept of social capital as applicable in order to understand the role of communities and collective action in a context of vulnerability and resilience. In this paper, I present results from a case study on the Isles of Scilly, UK. A mixed methods qualitative approach has been applied to analyse the various roles of social capital for the adaptation to climate change impacts on this small archipelago, which is representative of European small islands in an economically advanced, but isolated context. The Isles of Scilly are among the most vulnerable island regions in Europe. The results of the research contribute to the general discussion on social capital and the relevance of collective action for the adaptation to global climate change. How useful is the concept? And how relevant is it for small islands, such as the Isles of Scilly?

Read: Petzold, J. (2015): Limitations and opportunities of social capital for adaptation to climate change: a case study on the Isles of Scilly. The Geographical Journal. doi: 10.1111/geoj.12154
Online: onlinelibrary.wiley.com/doi/10.1111/geoj.12154/abstract
Contact: Jan Petzold (
jan.petzolddummy@uni-hamburgdummy2.de)

***

Date issued:  August 2015

The LatMix summer campaign: Submesoscale stirring in the upper ocean

Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for smaller-scale stirring processes. Here, the authors describe a major oceanographic field experiment aimed at observing and understanding the processes responsible for stirring at scales of 0.1–10 km. Stirring processes of varying intensity were studied in the Sargasso Sea eddy field approximately 250 km southeast of Cape Hatteras. Lateral variability of water-mass properties, the distribution of microscale turbulence, and the evolution of several patches of inert dye were studied with an array of shipboard, autonomous, and airborne instruments. Observations were made at two sites, characterized by weak and moderate background mesoscale straining, to contrast different regimes of lateral stirring. Analyses to date suggest that, in both cases, the lateral dispersion of natural and deliberately released tracers was O(1) m2 s–1 as found elsewhere, which is faster than might be expected from traditional shear dispersion by persistent mesoscale flow and linear internal waves. These findings point to the possible importance of kilometer-scale stirring by submesoscale eddies and nonlinear internal-wave processes or the need to modify the traditional shear-dispersion paradigm to include higher-order effects. A unique aspect of the Scalable Lateral Mixing and Coherent Turbulence (LatMix) field experiment is the combination of direct measurements of dye dispersion with the concurrent multiscale hydrographic and turbulence observations, enabling evaluation of the underlying mechanisms responsible for the observed dispersion at a new level.

Read: Shcherbina, A. Y., M. A. Sundermeyer, E. Kunze, E. D'Asaro, G. Badin, D. Birch, A.-M. E. G. Brunner-Suzuki, J. Callies, B. T. Kuebel Cervantes, M. Claret, B. Concannon, J. Early, R. Ferrari, L. Goodman, R. R. Harcourt, J. M. Klymak, C. M. Lee, M.-P. Lelong, M. D. Levine, R.-C. Lien, A. Mahadevan, J. C. McWilliams, M. J. Molemaker, S. Mukherjee, J. D. Nash, T. Özgökmen, S. D. Pierce, S. Ramachandran, R. M. Samelson, T. B. Sanford, R. K. Shearman, E. D. Skyllingstad, K. S. Smith, A. Tandon, J. R. Taylor, E. A. Terray, L. N. Thomas, and J. R. Ledwell (2015): The LatMix summer campaign: Submesoscale stirring in the upper ocean. Bull. Amer. Meteor. Soc., 96, 1257-1279.
doi: dx.doi.org/10.1175/BAMS-D-14-00015.1
Online: journals.ametsoc.org/doi/abs/10.1175/BAMS-D-14-00015.1
Contact: Gualtiero Badin (
gualtiero.badindummy@uni-hamburgdummy2.de)

***

Date issued:  20. July 2015

Analysis of geomorphic indices in the southern Central Andes (23° - 28° S): Evidence for pervasive Quaternary to Recent deformation in the Puna Plateau

Mountain-front sinuosity (Smf-) index was estimated for 189 first-order mountain fronts, as well as valley shape (Vf-) ratios and basin symmetry (T-) factors for 3366 second-order, tributary drainage basins. The correlation between known fault ages and Smf-indices shows that the indices can be used as a proxy to infer the ages of faults for which radiometric ages do not exist. Vf-ratios and Smf-indices point to pronounced Quaternary to Recent surface deformation on first-order reverse faults delimiting mountain fronts. By contrast, analysis of the transverse topographic symmetry (T-) factor, which has been used to assess rotational components of drainage basins, points to stochastic variations of erosion, possibly due to local lithological heterogeneity, rather than to a tectonic influence on basin geometry. Quaternary deformation of the upper crust in the Puna Plateau is apparently more pervasive than previously appreciated and has important ramifications for the Neogene to Recent morphotectonic evolution of the southern Central Andes.

Read: Daxberger, H. and U. Riller, (2015): Analysis of geomorphic indices in the southern Central Andes (23°–28° S): Evidence for pervasive Quaternary to Recent deformation in the Puna Plateau. Geomorphology, 248, 57-76.
Online: www.sciencedirect.com/science/article/pii/S0169555X15300817
Contact: Ulrich Riller (
ulrich.rillerdummy@uni-hamburgdummy2.de)

***

Date issued:  18. July 2015

The tectonic evolution of the south-eastern Terceira Rift/São Miguel region (Azores)

The eastern Azores Archipelago with São Miguel being the dominant subaerial structure is located at the intersection of an oceanic rift (Terceira Rift) with a major transform fault (Gloria Fault) representing the westernmost part of the Nubian-Eurasian plate boundary. Based on a seismic stratigraphy, we introduce a relative chrono-stratigraphic scheme for the entire study area, which suggests that the evolution of the southeastern Terceira Rift occurred in two stages. Considering age constrains from previous studies, we conclude that N140˚ structures developed orthogonal to the SW-NE direction of plate-tectonic extension before ~10 Ma. The N160˚ trending volcanic ridges and faults developed later as the plate tectonic spreading direction changed to WSWENE.

Read: Weiß, B.J., C. Hübscher, and T. Lüdmann, (2015): The tectonic evolution of the southeastern Terceira Rift/São Miguel region (Azores). Tectonophysics 654, 75-95, doi: 10.1016/j.tecto.2015.04.018.
Online: www.sciencedirect.com/science/article/pii/S0040195115002437
Contact: Benedikt Weiß (
benedikt.weissdummy@uni-hamburgdummy2.de)

***

Date issued:  16. July 2015

Influence of large offshore wind farms on North German climate

The influence of large offshore wind farms in the German Bight on North German climate is investigated with the numerical model METRAS. Depending on the weather situation, the impact of the wind farms varies from nearly no influence up to cloud cover changes over land. In summer mean, the urban heat island of Hamburg is slightly intensified.

Read: Boettcher, M., P. Hoffmann, H.-J. Lenhart, K. H. Schlünzen and R. Schoetter, (2015): Influence of large offshore wind farms on North German climate. Meteorologische Zeitschrift, DOI: 10.1127/metz/2015/0652.
Online: www.schweizerbart.de/papers/metz/detail/prepub/84921/Influence_of_large_offshore_wind_farms_on_North_German_climate
Contact: Marita Boettcher (
marita.boettcherdummy@uni-hamburgdummy2.de)

***

Date issued:  23. June 2015

Semi-automatic segmentation of petrographic thin section images using a “seeded-region growing algorithm” with an application to characterize wheathered subarkose sandstone

We present a new semi-automatic image segmentation workflow for the quantitative analysis of microscopic grain fabrics. The workflow uses an automated seeded region growing algorithm. The workflow is implemented in the open-source Geographic Information System (GIS) software SAGA, which provides all required tools for image analysis and geographic referencing.

Read: Asmussen, P., O. Conrad, A. Günther, M. Kirsch, and U. Riller, 2015: Semi-automatic segmentation of petrographic thin section images using a “seeded-region growing algorithm” with an application to characterize wheathered subarkose sandstone. Computers & Geosciences. Vol. 83, 89-99.
Online:
http://www.sciencedirect.com/science/article/pii/S0098300415001053http://www.sciencedirect.com/science/article/pii/S0098300415001053
Contact: Ulrich Riller (ulrich.rillerdummy@uni-hamburgdummy2.de)

***

Date issued:  05. June 2015

A new hierarchically-structured n -dimensional covariant form of rotating equations of geophysical fluid dynamics

We introduce n-dimensional covariant equations of geophysical fluid dynamics (GFD) valid on general manifolds and hierarchically-structured equations of GFD, in which these equations are split into metric-free and metric-dependent parts. For these equations we show that they conserve potential vorticity and that Kelvin's circulation theorem holds. As such n-dimensional formulations do not exist in vector calculus, we provide for both covariant and vector-invariant equations a representation on a rotating coordinate frame in an Euclidean space and compare these representations. This study reveals, among others, that the prognostic variables, described by differential forms, are independent of both metric and orientation. This makes them perfect descriptors of the fluid's quantities of interest, as they assign, analogously to physical measurement devices, real valued numbers to finite distances, areas, or volumes. This is not the case for prognostic variables described by (vector) proxy fields, as they depend on metric and orientation. Besides, this structuring has also practical benefits: since equations containing only topological structure are less complicated to implement and can be integrated exactly, our results may contribute to more efficient and accurate discretizations.

Read: Bauer, W., 2015: A new hierarchically-structured n-dimensional covariant form of rotating equations of geophysical fluid dynamics. GEM-International Journal on Geomathematics: 1-71.
Online:
http://link.springer.com/article/10.1007/s13137-015-0074-8http://link.springer.com/article/10.1007/s13137-015-0074-8#
Contact: Werner Bauer (wbauerdummy@physnet.uni-hamburgdummy2.de)

***

Date issued:  23. May 2015

Drivers of the 2013/14 winter floods in the UK

The paper examines critically an analysis of possible drivers behind the UK flooding in winter 2013/14, which was earlier published in the same journal. Two significant issues were noted, namely weak statistical links constructed across several steps, and the disregard of some, possibly even dominant explanatory drivers.

Read: van Oldenborgh, G.J., D. B. S. Stephenson, A. Sterl, R. Vautard, P. Yiou, S. S. Drijfhout, H. von Storch, and H. van den Dool, 2015: Drivers of the 2013/14 winter floods in the UK nature climate change 5, 490–491, doi:10.1038/nclimate2612
Online:
http://www.nature.com/nclimate/journal/v5/n6/full/nclimate2612.htmlhttp://www.nature.com/nclimate/journal/v5/n6/full/nclimate2612.html
Contact: Hans von Storch (
hvonstorchdummy@webdummy2.de)

***

Date issued:  18. May 2015

Climate change and military planning

The paper demonstrates that climate change has become an important issue for military planning. However, the directions in which it takes thinking about the future of armed forces differ widely. Among the six “military futures” identified, those linked to the function of disaster relief are most frequently found. However, the expansion of traditional military roles is also promoted. Rarer are suggestions for armed forces to became “greener” or “leaner”. In general, climate change provides an additional justification for continuing established paths for military planning.

Read: Brzoska, M., 2015: Climate change and military planning, International Journal of Climate Change Strategies and Management, Vol. 7 Iss: 2, pp.172 - 190
Online:
http://www.emeraldinsight.com/doi/abs/10.1108/IJCCSM-10-2013-0114http://www.emeraldinsight.com/doi/abs/10.1108/IJCCSM-10-2013-0114
Contact: Michael Brzoska (
brzoskadummy@ifshdummy2.de)

***

Date issued:  11. May 2015

Farmers' perceptions of and adaptation strategies to climate change and their determinants: the case of Punjab province, Pakistan

Based on farm households survey of 450 farmers in three ago-ecological zones in Punjab, Pakistan, in this study we examined the farm level perceptions of and adaptation to climate change and factors affecting the adoption of various adaptation measures. The study demonstrates that awareness of climate change is widespread in the area, and farmers are adapting their crops to climate variability. However the adaptation process is constrained due to several factors such as lack of information, lack of money, lack of resources and shortage of water. On the other hand Education, farming experience, access to various institutional services, weather forecasting information, are positively and significantly associated with adaptation to climate change in the study area.

Read: Abid, M., J. Scheffran, U. Schneider, and M. Ashfaq, 2015: Farmers' perceptions of and adaptation strategies to climate change and their determinants: the case of Punjab province, Pakistan, Earth Syst. Dynam., 6, 225-243, doi:10.5194/esd-6-225-2015.
Online:
http://www.earth-syst-dynam.net/6/225/2015/esd-6-225-2015.htmlhttp://www.earth-syst-dynam.net/6/225/2015/esd-6-225-2015.html
Contact: Muhammad Abid (
muhammad.abiddummy@uni-hamburgdummy2.de)

***

Date issued:  08. May 2015

Intercalibration of microwave temperature sounders using radio occultation measurements

Long-term satellite data records are becoming more and more important for climate research. This poses strong requirements on instrument calibration, which in the past has not been sufficiently rigorous. The article demonstrates how radio occultation measurements can be used to characterize and intercalibrate passive microwave temperature measurements.

Read: Isoz, O., S. A. Buehler, and P. Eriksson, 2015: Intercalibration Of Microwave Temperature Sounders Using Radio Occultation Measurements, J. Geophys. Res., 120, doi:10.1002/2014JD022699.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/2014JD022699/full
Contact: Stefan Bühler (
stefan.buehlerdummy@uni-hamburgdummy2.de)

***

Date issued:  May 2015

Visualization of 2D Uncertainty in Decadal Climate Predictions

Based on decadal prediction data from the MIKLIP project, we have looked at different software tools with the aim to jointly visualize simulation data and related uncertainty information. Since uncertainty information is also time dependent, an animated visualization of the combined data may help to gain a better understanding of the forecasts.

Read: Böttinger, M., H. Pohlmann, N. Röber, K. Meier-Fleischer and D. Spickermann, 2015: Visualization of 2D Uncertainty in Decadal Climate Predictions, EuroVis Workshop on Visualisation in Environmental Sciences (EnvirVis), Cagliari, (2015), (DOI: 10.2312/envirvis.20151083)
Online:
Contact: Michael Böttinger (boettingerdummy@dkrzdummy2.de)

Date issued:  18. May 2015

Why do conflicts over scarce renewable resources turn violent? A qualitative comparative analysis

Conflicts about renewable resources such as water, land, forests or fish are common in many regions of the world and are expected to rise in number, not at least due to climate change. Many of these conflicts remain non-violent, but some escalate into open violence with negative consequences for the affected societies. Using the method of qualitative comparative analysis (QCA), I analyze why conflicts over scarce renewable resources escalate violently. My approach bridges the gap between qualitative and quantitative analyses and shows that the combination of negative othering, low power differences and recent political change is crucial to explain why resource conflicts turn violent.

Read: Ide, T. (2015): Why do conflicts over scarce renewable resources turn violent? A qualitative comparative analysis. Global Environmental Change, 33, 61-70. dx.doi.org/10.1016/j.palaeo.2015.02.031
Online:
http://www.sciencedirect.com/science/article/pii/S0959378015000606
Contact: Tobias Ide (
tobias.idedummy@zmawdummy2.de)

***

Date issued:  15. May 2015

Climate change adaptation under a social capital approach – an analytical framework for small islands

Small islands are more vulnerable to the impacts of climate change than continental regions. Islands, however, feature a high degree of resilience through dense social networks, collective action, norms of reciprocity, relations of trust. The paper suggests a step-by-step approach to analyze potentials of social capital for the adaptation to climate change.

Read: Petzold, J., & B. M. Ratter (2015): Climate change adaptation under a social capital approach–An analytical framework for small islands. Ocean & Coastal Management, 112, 36-43.
Online:
http://www.sciencedirect.com/science/article/pii/S0964569115001179
Contact: Jan Petzold (
jan.petzolddummy@uni-hamburgdummy2.de)

***

Date issued:  11. May 2015

Variability patterns of the general circulation and sea water temperature in the North Sea

This model study investigates patterns of spatio-temporal variability in the North Sea general circulation and water temperature and their major driving mechanisms. Our results suggest that the leading natural modes of seasonal variability in the North Sea can be explained as a response to distinct variabilities in the wind field and heat flux forcing on various spatial and temporal scales. In particular, we identified driving mechanisms for specific circulation and temperature anomalies in winter that cannot be explained by the NAO but rather weaken the local correlations of the NAO index with volume transport and water temperature in the regions of Atlantic inflow.

Read: Mathis, M., A. Elizalde, U. Mikolajewicz,  & T. Pohlmann (2015). Variability Patterns of the General Circulation and Sea Water Temperature in the North Sea. Progress in Oceanography 135, 91-112, 2015, doi: dx.doi.org/10.1016/j.pocean.2015.04.009
Online:
http://www.sciencedirect.com/science/article/pii/S0079661115000695
Contact: Moritz Mathis (
moritz.mathisdummy@mpimet.mpgdummy2.de)

***

Date issued:  29. April 2015

Effects of climate-induced habitat changes on a key zooplankton species

Impacts of climate change on marine ecosystems have become increasingly apparent during the past decades. In consequence, it is necessary to study how these alterations can affect the habitat and population dynamics of key organisms. Here we used a video plankton recorder (VPR) to investigate the effect of climate-induced habitat changes on the copepod Pseudocalanus acuspes, a key species in the Baltic Sea. We compared the small-scale distribution of our target species during non-inflow and inflow periods. Our observations illustrate the strong impact that climate change can have on the habitat of key marine ecosystem species, important for overall ecosystem dynamics.

Read: Möller, K. O., J. O. Schmidt, M. S. John, A. Temming, R. Diekmann, J. Peters, ... & C. Möllmann (2015): Effects of climate-induced habitat changes on a key zooplankton species. Journal of Plankton Research, 37(3), 530-541.
Online:
http://plankt.oxfordjournals.org/content/early/2015/04/29/plankt.fbv033.full.pdf+html
Contact: Klas Möller (
klas.moellerdummy@uni-hamburgdummy2.de)

***

Date issued:  28. April 2015

Reanalyses of Anomalous Gravitational Microlensing Events in the OGLE-III Early Warning System Database with Combined Data

In a research project led by Uffe Jørgensen (Niels Bohr Institute), M. Burgdorf had carried out in the past astronomical observations with the aim of finding extra-solar planets of Earth mass and below by microlensing. The paper published now provides new solutions or additional information about events in the 2006-2008 period.  

Read: Jeong, J., H. Park, C. Han, A. Gould, A. Udalski, M. K. Szymański, ... & M. Hoffman (2015): Reanalyses of Anomalous Gravitational Microlensing Events in the OGLE-III Early Warning System Database with Combined Data. The Astrophysical Journal, 804(1), 38.
Online:
http://iopscience.iop.org/0004-637X/804/1/38l
Contact: Martin Burgdorf (
martin.joerg.burgdorfdummy@uni-hamburgdummy2.de)

***

Date issued:  16. April 2015

Long-term persistence enhances uncertainty about anthropogenic warming of Antarctica

In this study we investigate the strength and uncertainty of observed Antarctic temperatures. We find that the temperatures are strongly persistent and that previous studies have underestimated the uncertainties of the trend stengths. We argue that the persistent temperature fluctuations not only have a larger impact on regional warming uncertainties than previously thought but also may provide a potential mechanism for understanding the transient weakening (“hiatus”) of the regional and global temperature trends. 

Read: Ludescher, J., A. Bunde, C. L. Franzke & H. J. Schellnhuber (2015): Long-term persistence enhances uncertainty about anthropogenic warming of Antarctica. Climate Dynamics, 1-9.
Online:
http://link.springer.com/article/10.1007/s00382-015-2582-5
Contact: Christian Franzke (
christian.franzkedummy@uni-hamburgdummy2.de)

***

Date issued:  15. April 2015

Climate change vulnerability and adaptation options for the coastal communities of Pakistan

The study aims to explore climate change induced socio-economic vulnerability of mangrove-dependent communities in the Indus Delta. Our findings suggest that coastal communities of study area, either engaged with the fishery or agriculture sector, are not only exposed, but are also highly sensitive to climate change driven threats. Moreover, lack of access to basic facilities, inadequate income diversification, and low education levels are negatively affecting the adaptive capacity of the entire local population. However, the communities' nature of dwelling, their strong family networks, and their ability to migrate contribute positively to their adaptive capacity.

Read: Salik, K. M., S. Jahangir & S. ul Hasson (2015): Climate change vulnerability and adaptation options for the coastal communities of Pakistan. Ocean & Coastal Management, 112, 61-73.
Online:
http://www.sciencedirect.com/science/article/pii/S0964569115001209
Contact: Shabeh Ul Hasson (
shabeh.hassondummy@uni-hamburgdummy2.de)

***

Date issued:  7. April 2015

Spatial patterns in CO2 evasion from the global river network

CO2 evasion from rivers (FCO2) is an important component of the global carbon budget. Here we present the first global maps of CO2 partial pressures (pCO2) in rivers of stream orders 3 and higher and the resulting FCO2 at 0.5° resolution constructed with a statistical model. A geographic information system based approach is used to derive a pCO2 prediction function trained on data from 1182 sampling locations. While data from Asia and Africa are scarce and the training data set is dominated by sampling locations from the Americas, Europe, and Australia, the sampling locations cover the full spectrum from high to low latitudes. The predictors of pCO2 are net primary production, population density, and slope gradient within the river catchment as well as mean air temperature at the sampling location (r 2 = 0.47). The predicted pCO2 map was then combined with spatially explicit estimates of stream surface area Ariver and gas exchange velocity k calculated from published empirical equations and data sets to derive the FCO2 map. Using Monte Carlo simulations, we assessed the uncertainties of our estimates. At the global scale, we estimate an average river pCO2 of 2400 (2019–2826) μatmand a FCO2 of 650 (483–846) Tg C yr1 (5th and 95th percentiles of confidence interval). Our global CO2 evasion is substantially lower than the recent estimate of 1800 Tg C yr1 although the training set of pCO2 is very similar in both studies, mainly due to lower tropical pCO2 estimates in the present study. Our maps reveal strong latitudinal gradients in pCO2, Ariver, and FCO2. The zone between 10°N and 10°S contributes about half of the global CO2 evasion. Collection of pCO2 data in this zone, in particular, for African and Southeast Asian rivers is a high priority to reduce uncertainty on FCO2.

Read: Lauerwald, R., G. G. Laruelle, J. Hartmann, P. Ciais, and P. A. G. Regnier (2015): Spatial patterns in CO2 evasion from the global river network, Global Biogeochem. Cycles, 29, doi: 10.1002/2014GB004941.
Online:
http://onlinelibrary.wiley.com/doi/10.1002/2014GB004941/abstract
Contact: Jens Hartmann (
jens.hartmanndummy@uni-hamburgdummy2.de)

***

Date issued:  2. April 2015

The use of amino acid analyses in (palaeo-) limnological investigations: A comparative study of four Indian lakes in different climate regimes

Degradation and organic matter source indices commonly used for marine sediments are tested for their applicability in lakes. A new lake sediment degradation index (LI) derived from a principal component analysis of amino acid monomers can be used to classify the samples of four Indian lakes according to their state of organic matter degradation and might be applicable to other palaeo-lake investigations.

Read: Menzel, P., K. Anupama, N. Basavaiah, B.K. Das, B. Gaye, N. Herrmann, and S. Prasad, S., 2015: The use of amino acid analyses in (palaeo-) limnological investigations: A comparative study of four Indian lakes in different climate regimes. Geochimica et Cosmochimica Acta 160, 25-37.
Online:
http://www.sciencedirect.com/science/article/pii/S0016703715001702
Contact: Birgit Gaye (
birgit.gayedummy@uni-hamburgdummy2.de)

***

Date issued:  31. March 2015

Climate sciences meet visual arts

This set of comments reports experiences from a recent “science-meets-arts”-project in Germany, in which students from the University of Fine Arts in Hamburg (HFBK) shared day-to-day life in climate research groups for several months. The project was envisioned as a process of mutual inspiration with the aim of producing a joint exhibition and symposium at the end. This paper introduces the project as well as the subsequent commentaries and also presents some of my own observations.

Read: Rödder, S. (2015): Climate sciences meet visual arts. Journal of Science Communication, 14(01), C01-1.
Online:
http://jcom.sissa.it/archive/14/01/JCOM_1401_2015_C01
Contact: Simone Rödder (
simone.roedderdummy@uni-hamburgdummy2.de)

***

Date issued:  19. March 2015

Anomalous dispersion of sea ice in the Fram Strait region

The single-particle dispersion of sea ice in the Fram Strait region is investigated using ice drift buoys deployed from 2002 to 2009 within the Fram Strait Cyclones and the Arctic Climate System Study campaigns. A new method to estimate the direction of the mean flow, based on a satellite drift product, is introduced. As a result, the bias in the dispersion introduced by the mean flow is eliminated considering only the displacements of the buoys in the cross-stream direction. Results show an absolute dispersion growing quadratically in time for the first 3 days and an anomalous dispersion regime exhibiting a strongly self-similar scaling following a 5/4 power law for time scales larger than 6 days persisting over the whole time series of length 32 days. The non-Gaussian distribution of the velocity fluctuations with a skewness of &#8722;0.15 and a kurtosis of 7.33 as well as the slope of the Lagrangian frequency spectrum between &#8722;2 and &#8722;1 are in agreement with the anomalous diffusion regime. Comparison with data from the International Arctic Buoy Program yields similar results with an anomalous dispersion starting after 10 days and persisting over the whole time series of length 50 days. The results suggest the presence of deformation and shear acting on the sea ice dispersion. The high correlation between the cross-stream displacements and the cross-stream wind velocities shows the important role of the wind as a source for the anomalous dispersion.

Read: Gabrielski, A., G. Badin and L. Kaleschke, 2015: Anomalous dispersion of sea ice in the Fram Strait region, Journal of Geophysical Research, 120, 1809-1824, DOI: 10.1002/2014JC010359
Online:
http://onlinelibrary.wiley.com/doi/10.1002/2014JC010359/full
Contact: Gualtiero Badin (
gualtiero.badindummy@uni-hamburgdummy2.de)

***

Date issued:  19. March 2015

Transition to agroforestry significantly improves soil quality: A case study in the central mid-hills of Nepal

This paper analyses alterations of soil properties after the adoption of agroforestry practices in a typical mid-hill region of Nepal. Three agrosystems were compared with a special focus on soil fertility: (i) a mature, fully developed agroforestry system (AF); (ii) the predominant conventional system (CS) characterized by monocropping; and (iii) a system that has been in transition to AF for two years (TS). The results show significant differences in soil pH, aluminium content, base saturation, electric conductivity, organic matter and nitrogen content, and cation exchange capacity between AF and CS soils, indicating a higher soil quality and more fertile soil conditions in the AF soils.

Read: Schwab, N., U. Schickhoff & E. Fischer (2015): Transition to agroforestry significantly improves soil quality: A case study in the central mid-hills of Nepal. Agriculture, Ecosystems & Environment, 205, 57-69.
Online:
http://www.sciencedirect.com/science/article/pii/S016788091500078X
Contact: Udo Schickhoff (
udo.schickhoffdummy@uni-hamburgdummy2.de)

Date issued:  26. March 2015

What controls the size of a tropical cyclone? Investigations with an axisymmetric model

Processes controlling the size of tropical cyclones are still insufficiently understood. In this study a similarity relation has been derived that relates six model parameters to the horizontal extent of a steady-state tropical cyclone. Each parameter represents one of the following processes: Planetary rotation, condensation, radiative relaxation, horizontal diffusion, vertical diffusion, and surface transfer. The sensitivity to these parameters are investigated with the axisymmetric cloud model HURMOD. Individual variation of the parameters reveals that the radius of maximum horizontal wind speed (RMW) is very sensitive to the Coriolis parameter, the mixing lengths and the radiative relaxation time scale, whereas the radius of minimum tangential wind (RMINTW) merely depends on the Coriolis parameter, the surface transfer coefficients, and the radiative relaxation time scale. The increase of the RMW with vertical eddy-diffusivity goes along with an enhancement of the overturning mass flux within the secondary circulation. This agrees with the Hadley cell theory by Held and Hou who also emphasized the relevance of vertical diffusion. Moreover, TC size is found to be also sensitive to environmental conditions comprising the prescribed SST, tropopause height, and static stability.  

Read: Frisius, T., 2015: What controls the size of a tropical cyclone? Investigations with an axisymmetric model. Q.J.R. Meteorol. Soc.. doi: 10.1002/qj.2537
Online:
http://onlinelibrary.wiley.com/doi/10.1002/qj.2537/full
Contact: Thomas Frisius (thomas.frisius@zmaw.de)

***

Date issued:  13. March 2015

A Dynamical Systems Explanation of the Hurst Effect and Atmospheric Low-Frequency Variability

In this paper we provide an explanation of the long-range dependence phenomenon which is ubiquitous in climate time series. This phenomenon hampers the detection of externally forced trends. Here we show that the existence of this effect can be explained via regime behavior in the atmosphere.

Read: Franzke, C., S. Osprey, P. Davini and N. Watkins, 2015: A Dynamical Systems Explanation of the Hurst Phenomenon and Atmospheric Low-Frequency Variability, Scientific Reports, 5, 9068: doi: 10.1038/srep09068.
Online:
http://www.nature.com/srep/2015/150313/srep09068/full/srep09068.html
Contact: Christian Franzke (
christian.franzkedummy@uni-hamburgdummy2.de)

***

Date issued:  5. March 2015

Contrasting sea surface temperature of summer and winter monsoon variability in the northern Arabian Sea over the last 25 ka

Monsoonal upwelling in the Arabian Sea commenced during deglaciation at about 13 ka before present, peaked in the early Holocene between 11 and 8 ka, and decreased during the late Holocene. Centennial scale climate fluctuations are synchronous with those on the Asian continent and the northern high latitudes. Likely driving forces are insolation changes associated with sunspot cycles.

Read: Böll, A., H. Schulz, P. Munz, T. Rixen, B. Gaye, and K.-C. Emeis, 2015: Contrasting sea surface temperature of summer and winter monsoon variability in the northern Arabian Sea over the last 25 ka. Paleogeography, Paleoclimatology, Paleoecology 426, 10-21. dx.doi.org/10.1016/j.palaeo.2015.02.036
Online:
http://www.sciencedirect.com/science/article/pii/S003101821500108X
Contact: Birgit Gaye (
birgit.gayedummy@uni-hamburgdummy2.de)

***

Date issued:  March 2015

Evaluating Light Rain from Satellite- and Ground-Based Remote Sensing Data over the Subtropical North Atlantic

Three state-of-the-art satellite climatologies are analyzed for their ability to observe light rain from predominantly shallow, warm clouds over the subtropical North Atlantic Ocean trade winds (1998–2005). HOAPS composite (HOAPS-C), version 3.2; TMPA, version 7; and GPCP 1 Degree Daily (1DD), version 1.2, are compared with ground-based S-Pol radar data from the Rain in Cumulus over the Ocean (RICO; winter 2004/05) campaign and Micro Rain Radar data from the Barbados Cloud Observatory (2010–12). Winter rainfall amounts to one-third of annual rainfall, whereby light rain from warm clouds dominates. Daily rain occurrence and rain intensity during RICO largely differ among the satellite climatologies. TMPA best captures the frequent light rain events, only missing 7% of days on which the S-Pol radar detects rain, whereas HOAPS-C misses 33% and GPCP 1DD misses 56%. Algorithm constraints mainly cause these differences. In HOAPS-C also few available passive microwave (PMW) sensor overpasses limit its performance. TMPA outperforms HOAPS-C when only comparing nonmissing time steps, yet HOAPS-C can detect rain for S-Pol rain-covered areas down to 2%. In GPCP 1DD’s algorithm, the underestimated rain occurrence derived from PMW scanners is linked to the overestimated rain intensity, being constrained by the GPCP monthly satellite–gauge combination, whereby IR sensors determine the timing. Algorithm improvements in version 1.2 increased the rain occurrence by 50% relative to version 1.1. In version 7 of TMPA, algorithm corrections in PMW sounder data largely improved the rain detection relative to version 6. TMPA best represents light rain in the North Atlantic trades, followed by HOAPS-C and GPCP 1DD.

Read: Burdanowitz, J., L. Nuijens, B. Stevens, and C. Klepp, 2015: Evaluating Light Rain from Satellite- and Ground-Based Remote Sensing Data over the Subtropical North Atlantic. J. Appl. Meteor. Climatol., 54, 556–572. doi: dx.doi.org/10.1175/JAMC-D-14-0146.1
Online:
http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-14-0146.1
Contact: Christian Klepp (christian.klepp@zmaw.de)

***

Date issued:  28. February 2015

Carbonate isotopes from high altitude Tso Moriri Lake (NW Himalayas) provide clues to late glacial and Holocene moisture source and atmospheric circulation changes

Carbonate mineralogy and stable isotopic ratios of carbonates from the Tso Moriri were controlled by precipication during the early and by evaporation during the late Holocene. In this region of the NW Himalayas a late Holocene intensification of westerly winds was not pronounced.

Read: Mishra, P.K., S. Prasad, A. Anoop, B. Plessen, A. Jehangir, B. Gaye, P. Menzel, S.M. Weise, and A. R. Yousuf, 2015: Carbonate isotopes from high altitude Tso Moriri Lake (NW Himalayas) provide clues to late glacial and Holocene moisture source and atmospheric circulation changes. Palaeogeography, Palaeoclimatology, Palaeoecology 425, 76-83. dx.doi.org/10.1016/j.palaeo.2015.02.031
Online:
http://www.sciencedirect.com/science/article/pii/S0031018215001017
Contact: Birgit Gaye (birgit.gaye@uni-hamburg.de)

***

Date issued:  12. February 2015

Hydrodynamic Nambu brackets derived by geometric constraints

A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fractional Poisson equations for the stream-function are also included as results from the derivation. The formalism is extended to a hydrodynamic system coupled to a second degree of freedom, with the Rayleigh–Bénard convection as an example. This system is reformulated in terms of constitutive conservation laws with two additive brackets which represent individual processes: a first representing inviscid 2D hydrodynamics, and a second representing the coupling between hydrodynamics and thermodynamics. The results can be used for the formulation of conservative numerical algorithms that can be employed, for example, for the study of fronts and singularities.

Read: Blender, R., and G. Badin, 2015: Hydrodynamic Nambu brackets derived by geometric constraints. Journal of Physics A: Mathematical and Theoretical, 48(10), 105501.
Online:
http://iopscience.iop.org/1751-8121/48/10/105501
Contact: Gualtiero Badin (gualtiero.badin@uni-hamburg.de)

***

Date issued:  January 2015

The Impact of Regional Multidecadal and Century-Scale Internal Climate Variability on Sea Level Trends in CMIP5 Models

Regional sea level undergoes large changes during periods of years to decades.  These changes can mask the smaller but steadier changes due to global warming.  This paper describes how much the regional natural variability of sea level affects the projections of sea level rise expected from climate change.  For shorter-term periods of 20 years, regional sea level is still largely dominated by natural variability, but for longer-term periods of 100 years, the change in sea level from climate change is expected to be much larger nearly everywhere.  Natural variability may still play a part of sea level variability over these longer periods.

Read: Mark Carson, Armin Köhl, and Detlef Stammer, 2015: The Impact of Regional Multidecadal and Century-Scale Internal Climate Variability on Sea Level Trends in CMIP5 Models. J. Climate, 28, 853–861., doi: http://dx.doi.org/10.1175/JCLI-D-14-00359.1
Online: journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00359.1
Contact: Mark Carson (mark.carson@uni-hamburg.de)

Date issued:  2015-01-08
The Oceanic Shipboard Precipitation Measurement Network for Surface Validation – OceanRAIN

A new systematic long-term high quality shipboard precipitation data set is presented. Optical disdrometers are used to derive rain-, snow-, and mixed-phase precipitation through particle size distributions in minute-resolution. More than 5 million measurements are currently available. OceanRAIN aims at improving understanding of global ocean precipitation with special focus on validating satellite-, re-analysis and model data.

Read: Klepp, C., 2015: The Oceanic Shipboard Precipitation Measurement Network for Surface Validation – OceanRAIN.  Atmos. Res., doi:10.1016/j.atmosres.2014.12.014, in press.
Online:
http://www.sciencedirect.com/science/article/pii/S0169809515000034

Contact: Christian Klepp (christian.kleppdummy@zmawdummy2.de)

***

Date issued: January 2015

The German-Russian deep-sea expedition KuramBio (Kurile Kamchatka Biodiversity Studies) on board of the RV Sonne in 2012 following the footsteps of the legendary expeditions with RV Vityaz.

Read: Brandt, A. and M. Malyutina, 2015: The German–Russian deep-sea expedition KuramBio (Kurile Kamchatka biodiversity studies) on board of the RV Sonne in 2012 following the footsteps of the legendary expeditions with RV Vityaz, Deep Sea Research Part II: Topical Studies in Oceanography, Volume 111,Pages 1–9.
Online:
http://www.sciencedirect.com/science/article/pii/S0967064514003087

Contact: Angelika Brandt (ABrandtdummy@uni-hamburgdummy2.de)

***

Date issued:  January 2015
Seasonal Predictability over Europe Arising from El Niño and Stratospheric Variability in the MPI-ESM Seasonal Prediction System

We present results from a joint DWD-MPI-UHH seasonal prediction system, and show that predictive skill over Europe for the next winter is enhanced after El Nino events.

Read: Domeisen, D., A. H. Butler, K. Fröhlich, M. Bittner, W. A. Müller, and J. Baehr, 2015: Seasonal Predictability over Europe Arising from El Niño and Stratospheric Variability in the MPI-ESM Seasonal Prediction System. J. Climate, 28, 256–271.doi: dx.doi.org/10.1175/JCLI-D-14-00207.1.
Online:
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00207.1

Contact: Johanna Baehr (johanna.baehrdummy@uni-hamburgdummy2.de)

***

Date issued:  2014-11-20
Kinematics of Neogene to Recent upper-crustal deformation in the southern Central Andes (23°–28°S) inferred from fault–slip analysis: Evidence for gravitational spreading of the Puna Plateau

Based on new and compiled fault-kinematic data, in total 4746 brittle faults at 317 stations, we propose that the Puna Plateau and Eastern Cordillera have been undergoing horizontal shortening and gravitational spreading of the upper crust, whereas the topographically lower Pampean Ranges continue to undergo horizontal shortening only.

Read: Daxberger, H. and U. Riller, 2015: Kinematics of Neogene to Recent upper-crustal deformation in the southern Central Andes (23°-28°S) inferred from fault-slip analysis: Evidence for gravitational spreading of the Puna Plateau. Tectonophysics 642, 16-28.
Online:
http://www.sciencedirect.com/science/article/pii/S0040195114006404

Contact: Ulrich Riller (ulrich.rillerdummy@uni-hamburgdummy2.de)

***

Date issued:  2014-12-15
Glacial-interglacial changes in bottom-water oxygen content on the Portuguese margin

During the last and penultimate glacial maxima, atmospheric CO2 concentrations were lower than present, possibly in part because of increased storage of respired carbon in the deep oceans. The amount of respired carbon present in a water mass can be calculated from its oxygen content through apparent oxygen utilization; the oxygen content can in turn be calculated from the carbon isotope gradient within the sediment column. Here we analyse the shells of benthic foraminifera occurring at the sediment surface and the oxic/anoxic interface on the Portuguese Margin to reconstruct the carbon isotope gradient and hence bottom-water oxygenation over the past 150,000 years. We find that bottom-water oxygen concentrations were 45 and 65 μmol kg−1 lower than present during the last and penultimate glacial maxima, respectively. We calculate that concentrations of remineralized organic carbon were at least twice as high as today during the glacial maxima. We attribute these changes to decreased ventilation linked to a reorganization of ocean circulation and a strengthened global biological pump. If the respired carbon pool was of a similar size throughout the entire glacial deep Atlantic basin, then this sink could account for 15 and 20 per cent of the glacial PCO2 drawdown during the last and penultimate glacial maxima.

Read: Hoogakker, B.A.A., H. Elderfield, G. Schmiedl, I. N. McCave and R.E.M. Rickaby, 2015: Glacial-interglacial changes in bottom-water oxygen content on the Portuguese margin. Nature Geoscience 8, 40-43.
Online:
http://www.nature.com/ngeo/journal/v8/n1/full/ngeo2317.html

Contact: Gerhard Schmiedl (gerhard.schmiedldummy@uni-hamburgdummy2.de)

***

Date issued:  December 2014
A search for chaotic behavior in stratospheric variability: Comparison between the Northern and Southern Hemisphere

Southern Hemisphere (SH) stratospheric variability is investigated with respect to chaotic behavior using time series from three different variables extracted from four different re-analysis products. The results are compared with the same analysis applied to the Northern Hemisphere (NH). The probability density functions (PDFs) for the SH show persistent deviations from a Gaussian distribution. The variability is given by white spectra for low frequencies, a slope of -1 for intermediate frequencies and -3 slopes for high frequencies. Considering the time series for winter and summer separately, the PDFs show a Gaussian distribution and the variability spectra change their slopes, indicating the role of the transition between winter and summer variability in shaping the time series. The correlation and the Kaplan-Yorke fractal dimensions show that all dimensions display a large variability between different datasets and variables. This variability thus leaves open the question about the existence of a low-dimensional attractor or if the finite dimensions of the system are the result of the projection of a larger attractor in a low-dimensional embedding space.

Read: Badin, G. and D. I.V. Domeisen, 2014: A Search for Chaotic Behavior in Stratospheric Variability: Comparison between the Northern and Southern Hemispheres. J. Atmos. Sci., 71, 4611–4620. doi: dx.doi.org/10.1175/JAS-D-14-0049.1
Online:
http://www.liv.ac.uk/~gualti/papers/jas-d-14-0049.2E1.pdf

Contact: Gualtiero Badin (gualtiero.badindummy@zmawdummy2.de)

***

Date issued:  2014-11-08
The Normative Orientations of Climate Scientists

In 1942 Robert K. Merton tried to demonstrate the structure of the normative system of science by specifying the norms that characterized it. The norms were assigned the abbreviation CUDOs: Communism, Universalism, Disinterestedness, and Organized skepticism. Using the results of an on-line survey of climate scientists concerning the norms of science, this paper explores the climate scientists’ subscription to these norms.

Read: Bray, D., and H. von Storch, 2015: The Normative Orientations of Climate Scientists. Science and Engineering Ethic, online, openaccess, DOI: 10.1007/s11948-014-9605-1.
Online:
http://link.springer.com/article/10.1007/s11948-014-9605-1

Contact: Hans von Storch (hvonstorchdummy@webdummy2.de)

***

Date issued: 2014-10-15
Early 21st century snow cover state over the western river basins of the Indus River system

Based on improved MODIS Terra and Aqua daily snow products, we present a prevailing state of snow cover over the Hindukush-Karakoram-Himalayan river basins within the Indus basin. We find an additional proxy finding of positive changes in the existing frozen water resources and a potential for seasonal stream flow forecast for the studied basins.

Read: Hasson, S., V. Lucarini, M. R. Khan, M. Petitta, T. Bolch, and G. Gioli, 2014: Early 21st century snow cover state over the western river basins of the Indus River system, Hydrol. Earth Syst. Sci., 18, 4077-4100, doi:10.5194/hess-18-4077-2014.
Online: http://www.hydrol-earth-syst-sci.net/18/4077/2014/hess-18-4077-2014.html

Contact: Shabeh Hasson (shabeh.hassondummy@zmawdummy2.de)

Date issued:  2014-11-24
Marine regime shifts around the globe: theory, drivers, and impacts

The special issue, entitled "Marine regime shifts around the globe: theory, drivers, and impacts", in Philosophical Transactions of the Royal Society (edited by Alessandra Conversi [Italy], Christian Möllmann [Germany], Carl Folke [Sweden] & Martin Edwards [UK]) features more than 80 authors from different disciplines, across 6 continents. Altogether, the issue includes nearly 20 studies that explore the science behind regime shifts in ocean ecosystems worldwide, and how they can be managed.

Regime shifts are addressed from the different perspectives of theory, ecosystem observations, modelling and management. The articles featured in the special issue clearly tells us that there are regime shifts for many marine ecosystems, and that even small increases in human stressors can lead to abrupt major changes in their status.

Read: Möllman, C., C. Folke,M. Edwards and A. Conversi (2015): Marine regime shifts around the globe: theory, drivers and impacts. Phil. Trans. R. Soc. B 370: 20130260. dx.doi.org/10.1098/rstb.2013.0260

Conversi, A., V. Dakos, A. Gardmark, S. Ling, C. Folke, P. J. Mumby, C. Greene, M. Edwards, T. Blenckner, M. Casini, A. Pershing and C. Möllmann (2015): A holistic view of marine regime shifts. Phil. Trans. R. Soc. B 370: 20130279. dx.doi.org/10.1098/rstb.2013.0279

Levin, P. S., and C. Möllmann (2015): Marine ecosystem regime shifts: challenges and opportunities for ecosystem-based management. Phil. Trans. R. Soc. B 370: 20130275. dx.doi.org/10.1098/rstb.2013.0275

Fisher,  J. A. D., M. Casini, K. T. Frank, C. Möllmann, W. C Leggett and G. Daskalov (2015): The importance of within-system spatial variation in drivers of marine ecosystem regime shifts. Phil. Trans. R. Soc. B 370: 20130271. dx.doi.org/10.1098/rstb.2013.0271
Online:
http://classic.rstb.royalsocietypublishing.org/content/370/1659/20130260.short

Contact: Christian Möllmann (christian.moellmanndummy@uni-hamburgdummy2.de)

***

Date issued:  2014-11-14
On exposure, vulnerability and violence: Spatial distribution of risk factors for climate change and violent conflict across Kenya and Uganda

We conduct a risk analysis of climate change and violent conflict in Kenya and Uganda. The resulting maps show the hotspots for climate change-related violent conflicts in 2008. We compare our results with quantitative conflict data and qualitative case studies.

Read: Ide, T., J. P. Schilling, J. Link, J. Scheffran, G. Ngaruiya, and T. Weinzierl (2014): On exposure, vulnerability and violence: spatial distribution of risk factors for climate change and violent conflict across Kenya and Uganda, Political Geography 43 (1), online first, doi:10.1016/j.polgeo.2014.10.007.
Online:
http://www.sciencedirect.com/science/article/pii/S0962629814001036

Contact: Tobias Ide (tobias.idedummy@zmawdummy2.de)

***

Date issued:  November 2014
Detection and attribution of climate change signal in ocean wind waves.

Surface waves in the ocean respond to variability and changes of climate. Observations and modeling studies indicate trends in wave height over the past decades. Nevertheless, it is currently impossible to discern whether these trends are the result of climate variability or change. We used the output of an Earth system model (EC-Earth) produced within the 5th phase of the Coupled Model Intercomparison Project (CMIP5) to force a global wave model (WAM) in order to study the response of waves to different climate regimes. We ran a control simulation to determine the natural (unforced) model variability. Using a simplified fingerprint approach we calculated positive and negative limits of natural variability for wind speed and significant wave height which were then compared to different (forced) climate regimes over the historical period (1850-2010) and in the future climate change scenario RCP8.5 (2010-2100). We found detectable climate change signals in the current decade (2010-2020) in the North Atlantic, Equatorial Pacific and Southern Ocean. Until the year 2060, climate change signals are detectable in 60% of the global ocean area. We show that climate change acts to generate detectable trends in wind speed and significant wave height which exceed the positive and the negative ranges of natural variability in different regions of the ocean. Moreover, in more than 3% of the ocean area, the climate change signal is reversible, such that trends exceeded both positive and negative limits of natural variability in different points in time. We attribute these changes to local (due to local wind) and remote (due to swell) factors.

Read: Dobrynin, M., J. Murawski, J. Baehr, and T. Ilyina (2014): Detection and attribution of climate change signal in ocean wind waves. J. Climate. doi:10.1175/JCLI-D-13-00664.1, in press.
Online:
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00664.1

Contact: Mikhail Dobrynin (mikhail.dobrynindummy@zmawdummy2.de)

***

Date issued:  2014-10-18
Systematic physics constrained parameter estimation of stochastic differential equations

Here we develop a statistical method for estimating the parameters of stochastic climate models. The novel thing is that our method observes physical conservation laws like energy conservation and global stability. This makes our method very efficient.

Read: Peavoy, D., C. Franzke and G. O. Roberts (2014): Physics constrained parameter estimation of stochastic differential equations. Comp. Stat. Data Ana., 83, 182-199.
Online:
http://www.sciencedirect.com/science/article/pii/S016794731400303X

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

***

Date issued:  2014-10-06
Stochastic Climate Theory and Modeling

This is a review about current approaches of stochastic modelling of climate variability. In this paper we review the mathematical framework of stochastic climate modelling and describe current approaches for stochastic parameterizations in state-of-the-art weather and climate prediction models.

Read: Franzke, C. L. E., T. J. O'Kane, J. Berner, P. D. Williams, and V. Lucarini (2014): Stochastic Climate Theory and Modeling. WIREs Clim Change. doi: 10.1002/wcc.318
Online:
http://onlinelibrary.wiley.com/doi/10.1002/wcc.318/abstract

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

***

Date issued: 2014-10-02
Stoichiometric analysis of nutrient availability (N, P, K) within soils of polygonal tundra

In this paper we give a detailed overview on the limiting and available nutrients (N, P, K) within soils of the arctic polygonal tundra. By using a stoichiometric approach this work emphasizes the potentially limiting role of phosphorus for plant growth and microbial activity in the course of climate change.

Read: Beermann,F., A. Teltewskoi, C. Fiencke, E.-M. Pfeiffer and L. Kutzbach (2014): Stoichiometric analysis of nutrient availability (N, P, K) within soils of polygonal tundra, Biogeochemistry, doi: 10.1007/s10533-014-0037-4.
Online:
http://link.springer.com/article/10.1007/s10533-014-0037-4#

Contact: Fabian Beermann (fabian.beermanndummy@uni-hamburgdummy2.de)

***

Date issued: October 2014
Periplatform drift: The combined result of contour current and off-bank transport along carbonate platforms

Hydroacoustic and sedimentological data from the western leeward flank of the Great Bahama Bank acquired with RV METEOR in 2013 during the cruise M95 document the interplay of off-bank sediment export, along-slope transport, and erosion, which together shape facies and thickness distribution of slope carbonates. The integrated data set depicts the combined product of these processes and allows formulation of a comprehensive model of a periplatform drift that significantly amends established models of carbonate platform slope facies distribution and geometry.

Read: Betzler, C., S. Lindhorst, G. P. Eberli, T. Lüdmann, J. Möbius, J. Ludwig,I. Schutter, M. Wunsch, J. J.G. Reijmer,and C. Hübscher  (2014): Periplatform drift: The combined result of contour current and off-bank transport along carbonate platforms. Geology, 42(10): 871-874. doi: 10.1130/G35900.1
Online:
http://geology.gsapubs.org/content/42/10/871.abstract

Contact: Christian Betzler (christian.betzlerdummy@uni-hamburgdummy2.de)

***

Date issued: 2014-09-01
Urban air temperature anomalies and their relation to soil moisture observed in the city of Hamburg

The spatial variability of the urban air temperature for Hamburg is analyzed based upon a one-year dataset of meteorological and pedological network measurements. The nocturnal urban heat island is identified and averages + 1.7K at inner city stations, + 0.7K at a suburban housing area and + 0.3K at a nearby green space. Air temperature anomalies during daytime show an annual mean deviation of - 0.5K above unsealed, vegetated surfaces from a sealed site during days with a turbulent mixing induced by wind speed > 2ms-1. Here, there is an indication for a relation between the water content of upper soil layers and the warming of air.

Read: Wiesner, S., A. Eschenbach, F. Ament (2014): Urban air temperature anomalies and their relation to soil moisture observed in the city of Hamburg, Meteorologische Zeitschrift, 23, 143-157. DOI: 10.1127/0941-2948/2014/0571.
Online:
www.schweizerbart.de/papers/metz/detail/23/84226/Urban_air_temperature_anomalies_and_their_relation_to_soil_moisture_observed_in_the_city_of_Hamburg

Contact: Sarah Wiesner (sarah.wiesnerdummy@uni-hamburgdummy2.de)

***

Date issued:  September 2014
Linear and Nonlinear Trends of Extreme Temperatures in Korea

This study examines the trends in extreme temperatures of 11 stations in Korea using quantile regression. We find that the trend in cold extremes is stronger than in warm extremes.

Read: Kim, S.-W., K. Song, S.-Y. Kim, S.-W. Son and C. Franzke (2014): Linear and nonlinear trends of extreme temperatures in Korea. Atmosphere (in Korean), 24, 379-390.
Online:
http://www.dbpia.co.kr/Journal/ArticleDetail/3516935

Contact: Christian Franzke (christian.franzkedummy@uni-hamburgdummy2.de)

Date issued: 2014-09-29
A violent mid-latitude storm in Northern Germany and Denmark, 28 October 2013

A strong storm on 28 October 2013 over northern Germany and southern Denmark fits a slight increase in storminess during recent decades. However, the increase constitutes part of multidecadal variability.

Read: von Storch, H., F. Feser, S. Haeseler, C. Lefebvre and M. Stendel (2014): Explaining Extreme Events of 2013 From a Climate Perspective, Special Supplement to the Bulletin of the American Meteorological Society, Vol. 95, No. 9, September 2014.
Online:
http://www2.ametsoc.org/ams/assets/File/publications/BAMS_EEE_2013_Full_Report.pdf
Contact: Hans von Storch (
hvonstorchdummy@webdummy2.de)

***

Date issued: 2014-09-16
On the role of non-uniform stratification and short-wave instabilities in three-layer quasi-geostrophic turbulence

Ocean currents undergo instabilities which have a typical size that corresponds to the size of eddies observed for example in spectacular satellite pictures. However, the ocean is also filled with dynamics at scales smaller than this typical scale. The question on how to represent, mathematically, these instabilities is still open and is explored in this paper. The aim is to find one of the simplest ways to represent the instabilities. Results might be used for the study of these small scale instabilities in climate models that are currently unable to resolve them.

Read: Badin, G. (2014): On the role of non-uniform stratification and short-wave instabilities in three-layer quasi-geostrophic turbulence, Physics of Fluids, 26, 09660, doi: http://dx.doi.org/10.1063/1.4895590.
Online:
http://scitation.aip.org/content/aip/journal/pof2/26/9/10.1063/1.4895590
Contact: Gualtiero Badin (
gualtiero.badindummy@zmawdummy2.de)

***

Date issued:  2014-08-30
Operationalizing climate targets under learning: An application of cost-risk analysis

The article presents the expected economic value of perfect climate information under a 2° target for a 66% compliance level. This became possible through a new decision-analytic tool as a hybrid of two competing climate economic schools of thought (cost benefit vs. climate target-oriented approaches) that was further developed. Up to 1/3 of mitigation costs could be saved through improved climate information accordingly.

Read: Neubersch, D., H. Held, A. Otto (2014): Operationalizing climate targets under learning: An application of cost-risk analysis, Climatic Change, 126:305-318, DOI: 10.1007/s10584-014-1223-z.
Online:
http://link.springer.com/article/10.1007%2Fs10584-014-1223-z#page-1
Contact: Hermann Held (
hermann.helddummy@zmawdummy2.de)

***

Date issued: 2014-08-25
Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

We investigated the palynology of sediment cores from the New Jersey shallow shelf to examine vegetation and climate dynamics on the east coast of North America between 33 and 13 million years ago. We conclude that vegetation and regional climate in the region did not react as sensitively to Oligocene and Miocene climate changes as other regions in North America or Europe due to the moderating effects of the North Atlantic and that an uplift of the Appalachian Mountains during the Miocene may have resulted in vegetation shifts during the Middle Miocene.

Read: Kotthoff, U., D. R. Greenwood,F. M. G.  McCarthy, K. Müller-Navarra, S.  Prader and S. P. Hesselbo (2014): Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027), Climate Past, 10, 1523-1539. DOI: 10.5194/cp-10-1523-2014.
Online:
www.clim-past.net/10/1523/2014/cp-10-1523-2014.html
Contact: Ulrich Kotthoff (
ulrich.kotthoffdummy@uni-hamburgdummy2.de)

***

Date issued:  2014-08-07
Late Holocene primary productivity and sea surface temperature variations in the northeastern Arabian Sea: Implications for winter monsoon variability

Our high-resolution reconstruction of primary productivity and alkenone-derived SST from the northeastern Arabian Sea provides a unique record of winter monsoon variability throughout the late Holocene. Winter monsoon increased from 250 to about 1900 A.D.  in response to the overall southward movement of average ITCZ location. The coherence between monsoon-induced variations over the Pakistan Margin with other monsoon records indicates a strong linkage of climate variability in the entire Asian monsoon system during the late Holocene.

Read: Böll, A., A. Lückge,P. Munz, S. Forke, H. Schulz, V. Ramaswamy, T. Rixen, B. Gaye, K.-C. Emeis (2014): Late Holocene primary productivity and sea surface temperature variations in the northeastern Arabian Sea: Implications for winter monsoon variability, Paleoceanography, 29 (8), 778-794. DOI: 2013PA002579.
Online:
http://onlinelibrary.wiley.com/enhanced/doi/10.1002/2013PA002579/
Contact: Anna Böll (
anna.boelldummy@zmawdummy2.de), Birgit Gaye (birgit.gayedummy@zmawdummy2.de)

***

Date issued: 2014-07-31
Adaptation to New Climate by an Old Strategy? Modeling Sedentary and Mobile Pastoralism in Semi-Arid Morocco

We show in a regional modeling study for southern Morocco that mobile pastoralism is merely affected by a 20% decrease of precipitation. In contrast, the increasingly adopted strategy of sedentary pastoralism shows significant reductions of income by 18% - 44% under the same scenario.

Read: Freier, K. P., M. Finckh and U. A. Schneider (2014): Adaptation to New Climate by an Old Strategy? Modeling Sedentary and Mobile Pastoralism in Semi-Arid Morocc,  Land, 3(3), 917-940. DOI:10.3390/land3030917.
Online:
http://www.mdpi.com/2073-445X/3/3/917
Contact: Korbinian Freier (korbinian.freierdummy@zmawdummy2.de)

***

Date issued: 2014-07-25
Climate-related flood risks and urban responses in the Pearl River Delta, China

This paper jointly investigates climate change trends, impacts on flood events, flood vulnerability and risk, and response strategies in the Pearl River Delta (PRD), a rapidly urbanizing coastal area in southeast China. Our analysis based on a reanalysis dataset and model projections are integrated with literature results, which indicate a climate scenario of increasing mean temperature, precipitation, sea level, typhoon intensity, and the frequency of extreme weather events in the PRD. These trends, together with the continuing urbanization in flood-prone areas, are expected to increase flood frequency and aggravate both the scale and degree of flooding in the PRD area. We further estimate the flood vulnerability of the 11 PRD cities using the indicator system method. The results suggest that the exposure and sensitivity of central cities (Hong Kong, Macao, Shenzhen, and Guangzhou) are very high because of highly exposed populations and assets located in lowland areas. However, the potential vulnerability and risk can be low due to high adaptive capacities (both by hard and soft flood-control measures). We further suggest that the flood risks can be mitigated by developing an integrated climate response strategy, releasing accurate early warning and action guidance, sharing flood-related information, and applying the advantages of online social network analysis.

Read: Yang, L., J. Scheffran, H. Qin and Q. You (2014): Climate-related flood risks and urban responses in the Pearl River Delta, China, Regional Environmental Change.
25 Jul 2014
Online: http://link.springer.com/article/10.1007%2Fs10113-014-0651-7
Contact: Liang Yang (
liang.yangdummy@zmawdummy2.de)

***

Date issued: 2014-07-15
Macroscopic Failure Processes at Mines Revealed by Acoustic Emission (AE) Monitoring

Studying the spatio temporal evolution of microcracking (mm to cm long cracks), in the mining environment caused by human induced stresses, illuminates regions which are close to failure. By evaluating an extensive catalogue of so-called acoustic emissions (mm to cm scale cracking events recorded with sensors working like microphones) an extended and expanding macrocrack with an extent of about 10 metres close to an underground cavity was identified. The growth of such a macrocrack is indicated by microcracking along its perimeter. Such a growing macrocrack can indicate the site of future catastrophic rock failure in the mining environment and may also be a model for the earthquake nucleation process.

Read: Becker, D., B. Cailleua, D. Kaiser and T. Dahm (2014): Macroscopic Failure Processes at Mines Revealed by Acoustic Emission (AE) Monitoring, Bull. Seismol. Soc. Am., 104 (4), 1785-1801. DOI: 10.1785/0120130286.
Online:
www.bssaonline.org/content/early/2014/07/09/0120130286.abstract
Contact: Dirk Becker (
dirk.beckerdummy@zmawdummy2.de)

***

Date issued: 2014-07-10
Tidal controls on trace gas dynamics in a seagrass meadow of the Ria Formosa lagoon (southern Portugal)

Coastal zones are important source regions for a variety of trace gases. Here we report results obtained using a newly developed dynamic flux chamber system for carbon dioxide (CO2), methane (CH4) and a variety of hydrocarbons, halocarbons and sulphur-bearing compounds from a seagrass dominated intertidal area. The high time resolved CO2 and CH4 flux measurements over full tidal cycles revealed a complex dynamic mediated by tide and light. In contrast to most previous studies our data indicate significantly enhanced fluxes during tidal immersion relative to periods of air exposure.

Read: Bahlmann, E., I. Weinberg, J.V.  Lavrič, T. Eckhard, W. Michaelis, R. Santo, and R. Seifert (2014): Tidal controls on trace gas dynamics in a seagrass meadow of the Ria Formosa lagoon (southern Portugal),  Biogeosciences Discuss., 11, 10571-10603. DOI: 10.5194/bgd-11-10571-2014
Online:
www.biogeosciences-discuss.net/11/10571/2014/
Contact: Richard Seifert (richard.seifertdummy@zmawdummy2.de)

***

Date issued: 2014-07-10
A halocarbon survey from a seagrass dominated subtropical lagoon, Ria Formosa (Portugal): flux pattern and isotopic composition

Monohalomethanes (CH3Cl, CH3Br, CH3I) and bromoform (CHBr3) are prominent precursors of reactive halogens which affect the oxidative capacity of the atmosphere and initiate stratospheric ozone destruction. Furthermore, CH3I may further contribute to the formation of aerosols in the marine boundary layer. Coastal zones are reported being vital source regions of halocarbons. However, seagrass meadows, though being one of the most productive ecosystems with a similar global abundance as mangroves and salt marshes, are relatively little studied so far.

We report fluxes and δ13C-values of halomethanes obtained in the seagrass dominated subtropical lagoon Ria Formosa, Portugal by dynamic flux chamber measurements. Observed variation in fluxes and isotopic composition are attributed to diurnal cycles, tidal effects, and the variety of possible sources and sinks in the seagrass meadows. A rough global upscaling of our data suggests a minor contribution from seagrass meadows to the global production of < 1% for CH3Cl and CH3Br.

Read: Weinberg, I., E. Bahlmann, T.  Eckhardt, W.  Michaelis  and R. Seifert (2014): A halocarbon survey from a seagrass dominated subtropical lagoon, Ria Formosa (Portugal): flux pattern and isotopic composition, Biogeosciences Discuss., 11, 10605-10646. DOI: 10.5194/bgd-11-10605-2014.
Online:
www.biogeosciences-discuss.net/11/10605/2014/
Contact: Richard Seifert (
richard.seifertdummy@zmawdummy2.de)

***

Date issued:  07/2014
Norddeutscher Klimamonitor – Klimazustand und Klimaentwicklung in Norddeutschland innerhalb der letzten 60 Jahre (1951-2010)

Der norddeutsche Klimamonitor ist ein Informationsprodukt, das vom Norddeutschen Klimabüro des Helmholtz-Zentrums Geesthacht und vom Regionalen Klimabüro Hamburg des Deutschen Wetterdienstes entwickelt wurde, um über den aktuellen Forschungsstand zum Klima und bisherigen Klimawandel in Norddeutschland zu informieren. Dazu wurden Stationsmessungen des DWD-Messnetzes und messbasierte Flächendatensätze sowie Reanalysen aus dem coastDat-Datensatz für Norddeutschland ausgewertet und auf einer Webseite grafisch veranschaulicht. Innerhalb der letzten 60 Jahre weisen alle Datensätze eine Erwärmung von etwa 1,2 K in Norddeutschland auf. Zudem ist die beobachtete Erwärmung der letzten 30 Jahre als exemplarisch für die künftig zu erwartende Erwärmung einzustufen.

Read: Meinke, I., M. Maneke, W. Rieck and B. Tinz, B. (2014): Mitteilungen DMG 01/2014. Online: dmg-ev.de/gesellschaft/publikationen/documents/Norddeutscher_Klimamonitor.pdf Contact: Insa Meinke (Insa.Meinke@hzg.de)

Date issued: 2014-07-25

On climate, conflict and cumulation: suggestions for integrative cumulation of knowledge in the research on climate change and violent conflict.

We provide an extensive review of the current literature on climate change and conflict and identify three obstacles to the integrative cumulation of knowledge in this field of research. First, evidence on the links between adverse environmental change and peace/cooperation is hardly considered. Second, large-N studies, which constitute the dominant methodological account in the research field, suffer from various data problems. Third, some key terms are used in an imprecise, misleading or ambiguous way. As an alternative, an integrative theoretical framework for the environmental peace perspective is developed.

Read: Ide, T., Scheffran, J., 2014, On climate, conflict and cumulation: suggestions for integrative cumulation of knowledge in the research on climate change and violent conflict, Global Change, Peace and Security, 26 (3).

Online: http://www.tandfonline.com/doi/full/10.1080/14781158.2014.924917#.U9ZVEkCO5BA

Contact: tobias.idedummy@zmawdummy2.de

 

***

Date issued: 2014-07-08

Representative wavelengths absorption parameterization applied to satellite channels and spectral bands

Climate models require fast radiation schemes to calculate energy fluxes. Furthermore, remote sensing also requires fast radiation schemes for sensor simulation. In both cases, precise calculations are computationally expensive, because the radiative transfer equation has to be solved for many frequencies, and then integrated. A way around this is to approximate the integral by a sum over a much smaller number of representative frequencies. Traditional fast radiation schemes, such as correlated-k schemes, already use this idea. But we have found a way to derive the representative frequencies more rigorously, using an established numerical method called simulated annealing. The article applies the simulated annealing method to derive parameterizations for broadband radiative transfer calculations in the visible spectral range, and also for a number of visible range satellite sensors. Absorption cross-sections for the selected frequencies are also pre-calculated (with the Atmospheric Radiative Transfer Simulator ARTS), so that the article can form the basis of a complete new fast radiation scheme for the shortwave spectral range. The parameterization is planned to be available together with the LibRadTran radiative transfer package.

Read: Gasteiger, J., C. Emde, B. Mayer, R. Buras, S.A. Buehler, O. Lemke, 2014, Representative wavelengths absorption parameterization applied to satellite channels and spectral bands, Journal of Quantitative Spectroscopy and Radiative Transfer, 148, 99-115, ISSN 0022-4073.

Online: http://www.sciencedirect.com/science/article/pii/S0022407314002842

Contact: stefan.buehlerdummy@uni-hamburgdummy2.de

 

***

Date issued: 2014-07-02

A note on the symmetric and antisymmetric constituents of weakly-nonlinear solutions of classical wind-driven ocean circulation models

A classical model of wind-driven ocean circulation is studied in the weakly nonlinear approximation. An asymptotic expansion for small Rossby number is applied to the separate symmetric and asymmetric components of the stream function, where the symmetry refers to a north-south reflection transformation. Results show that the asymmetric component is responsible for the formation of steady cyclones and anticyclones that cause the deformation of the total stream function of the system. Higher-order components of the stream function in the asymptotic expansion are forced by an effective stress that acts only to redistribute vorticity.

Read: Crisciani, F., G. Badin, 2014, A note on the symmetric and antisymmetric constituents of weakly-nonlinear solutions of classical wind-driven ocean circulation models, European Physical Journal Plus, 129: 142 DOI: 10.1140/epjp/i2014-14142-y.

Online: http://link.springer.com/article/10.1140/epjp/i2014-14142-y

Contact: gualtiero.badindummy@zmawdummy2.de

 

***

Date issued: 2014-06-23

Climate change, environmental violence and genocide

National, ethnic and religious differences are common causes of violence, persecution and even genocide. However, there has been little research on the effects of climate changes such as  drought, flooding or loss of territory – thereby ignoring a major potential cause of violence. In an effort to raise academic awareness and promote discussion of the topic Prof. Jürgen Zimmerer, a historian at Universität Hamburg and Principal Investigator at CliSAP, has now edited a special issue of the “International Journal of Human Rights.”

Read: Zimmerer, J., 2014, Climate change, environmental violence and genocide, The Int. Journ. of Human Rights: Special Issue, 18 (3), 263-280.

Online: http://www.tandfonline.com/toc/fjhr20/current#.U84jybFpLLl

Contact: juergen.zimmerer@uni-hamburg.de

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Date issued: 2014-06-23

Violent climate or climate of violence? Concepts and relations with focus on Kenya and Sudan

This article elaborates on the various, complex and often indirect causal pathways which potentially link climate change to violent conflict. The importance of individuals’ capabilities and motivations as well as recursive feedback loops which can trigger a spiral of violence is highlighted. The theoretical framework is applied to analyse pastoral conflicts in northwestern Kenya and civil war in Sudan.

Read: Scheffran, J., T. Ide, J.-P. Schilling, 2014, Violent climate or climate of violence? Concepts and relations with focus on Kenya and Sudan, The Int. Journ. of Human Rights: Special Issue, 18 (3), 369-390.

Online: http://www.tandfonline.com/doi/full/10.1080/13642987.2014.914722#.U84hYbFpLLm

Contact: juergen.scheffrandummy@zmawdummy2.de

 

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Date issued: 2014-06-19

Polar gravel beach-ridge systems: Sedimentary architecture, genesis, and implications for climate reconstructions (South Shetland Islands / Western Antarctic Peninsula)

The sedimentary architecture of polar gravel-beach ridges is presented and it is shown that ridge internal geometries reflect past wave-climate conditions. Development of individual ridges is seen to result from multiple storms in periods of increased storm-wave impact on the coast. Strand-plain progradation, by contrast, is the result of swash sedimentation at the beach-face under persistent calm conditions. Sheltered areas exhibit numerous low ridges, exposed coasts fewer but larger ridges. More complete climate records are expected from beach ridges on sheltered coasts.

Read: Lindhorst, S., I. Schutter, 2014, Polar gravel beach-ridge systems: Sedimentary architecture, genesis, and implications for climate reconstructions (South Shetland Islands / Western Antarctic Peninsula), Geomorphology, 221: 187-203.

Online: http://www.sciencedirect.com/science/article/pii/S0169555X14003134

Contact: sebastian.lindhorstdummy@uni-hamburgdummy2.de


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Date issued: 2014-06-10

Linking Holocene drying trends from Lonar Lake in monsoonal central India to North Atlantic cooling events

In a well-dated sediment core from Lonar Lake Holocene climate could be resolved in detail. A gradual transition from a wet early Holocene to a more arid late Holocene was observed between 6.2 and 3.9 ka cal BP. Two periods of prolonged droughts were possibly related to shifts in the position of the Indo Pacific Warm Pool. Short term drying events with a periodicity of 1.5 ka could be correlated with cold periods in the North Atlantic; these centennial climate fluctuations were possibly triggered by variations in solar activity.

Read: Menzel, P., B. Gaye, P. K. Mishra, A. Anoop, N. Basavaiah, N. Marwan, B. Plessen, S. Prasad, N. Riedel, M. Stebich, M. G. Wiesner, 2014, Linking Holocene drying trends from Lonar Lake in monsoonal central India to North Atlantic cooling events, Palaeogeography, Palaeoclimatology, Palaeoecology 410, 164-178.

Online: http://www.sciencedirect.com/science/article/pii/S0031018214003009

Contact: philip.menzeldummy@zmawdummy2.de, birgit.gayedummy@zmawdummy2.de, martin.wiesnerdummy@zmawdummy2.de

 

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Date issued: 2014-06-07

The ValleyMorph Tool: An automated extraction tool for transverse topographic symmetry (T-) factor and valley width to valley height (Vf-) ratio

In tectonically active regions on Earth, shallow-crustal deformation associated with seismic hazards may pose a threat to human life and property. The study of landform development, such as analysis of the valley width to valley height ratio (Vf-ratio) and the Transverse Topographic Symmetry Factor (T-factor), delineating drainage basin symmetry, can be used as a relative measure of tectonic activity along fault-bound mountain fronts. We present a newly developed, Python based, ESRI ArcGIS compatible tool and stand-alone script, the ValleyMorph Tool. This tool facilitates an automated extraction of the Vf-ratio and the T-factor data for large regions based on a digital elevation raster and watershed polygon files as input.

Read: Heidi Daxberger, Ron Dalumpines, Darren M. Scott, Ulrich Riller, 2014. The ValleyMorph Tool: An Automated Extraction Tool for Transverse Topographic Symmetry (T-) Factor and Valley Width to Valley Height (Vf-) Ratio. Computer and Geosciences 70, 154-163.

Online: http://dx.doi.org/10.1016/j.cageo.2014.05.015

Contact: ulrich.rillerdummy@uni-hamburgdummy2.de

 

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Date issued: 2014-05-28

The Brazilian experience of flex-fuel vehicles technology: towards low carbon mobility.

Emerging countries are central to the climate change policy, in which the transport system plays a key role. These countries still have the majority of their traffic infrastructure based on individual-mobility meaning that public transport and alternative means of transport are not a priority yet. It is argued in the study that the FFV technology developed in Brazil is an important mitigation initiative towards low-carbon urban centers. Results show how some institutional aspects in this Brazilian industry were crucial to turn this technology – initially developed to contribute to the country´s energy security – into a very successful example of mitigation in the national mobility sector.

Read: Vieira do Nascimento, D., The Brazilian experience of flex-fuel vehicles technology: towards low carbon mobility. In: C.A. Brebbia, J.W.S. Longhurst. (Org.). Urban Transport XX. 1ed.: WIT Press, 2014, v. 138, p. 545-555.

Online: http://www.witpress.com/transport-engineering.html

Contact: daniele.nascimentodummy@zmawdummy2.de

 

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Date issued: 2014-05-14

Fault-controlled evaporite deformation in the Levant Basin, Eastern Mediterranean

During the Messinian Salinity Crisis a multi-layered salt giant of 1.5 km thickness was precipitated in the Levant Basin, easternmost Mediterranean Sea.  Internal deformation of this geologically young salt layer was commonly explained by gravity-driven processes only. Based on high-quality depth-migrated seismic data, we show for the first time how evaporites have also deformed in response to a sub-salt extensional fault system, adding another, tectonically-controlled deformation mechanism to drive salt tectonics in the Levant Basin. Integrating these new findings and previous results into a new conceptual compilation shows how the original shape of the Messinian salt was altered by a set of spatially and temporally variable salt-tectonic driving mechanisms, making the Levant Basin an excellent site to study salt tectonics in its initial stage.

Read: Reiche, S., C. Hübscher, M. Beitz, 2014, Fault-controlled evaporite deformation in the Levant Basin, Eastern Mediterranean. Marine Geology., 354.

Online: http://www.sciencedirect.com/science/article/pii/S0025322714001200

Contact: soenke.reiche@zmaw.de, christian.huebscher@zmaw.de

Date issued: 2014-05-27

SMOS-derived thin sea ice thickness: algorithm baseline, product specifications and initial verification

A new iterative algorithm to retrieve the sea ice thickness from SMOS satellite data has been developed. The satellite method was validated with airborne measurements of the sea ice thickness and compared with estimates from assimilation systems.

Read: Tian-Kunze, X., Kaleschke, L., Maaß, N., Mäkynen, M., Serra, N., Drusch, M., and Krumpen, T.: SMOS-derived thin sea ice thickness: algorithm baseline, product specifications and initial verification, The Cryosphere, 8, 997-1018.

Online: http://www.the-cryosphere.net/8/997/2014/tc-8-997-2014.html

Contact: lars.kaleschkedummy@zmawdummy2.de

 

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Date issued: 2014-05-22

Climate-driven changes in chemical weathering and associated phosphorus release since 1850: Implications for the land carbon balance

Chemical weathering and associated nutrient release act as a control on atmospheric carbon dioxide (CO2) concentration. To globally quantify the contribution of chemical weathering and associated phosphorus (P) release on the historical trend in terrestrial carbon uptake, we applied a weathering model under climate reconstructions from four Earth System Models. In these simulations, CO2 consumption and P release increased from 1850 to 2005 by 11 ± 3% and 12 ± 4%, respectively. Thereby the intensification of weathering due to climate change could have contributed to a small extent to the trend in terrestrial carbon uptake since the pre–Industrial Period. Using a back of the envelope calculation, we found a feedback strength of CO2 consumption and P release of −0.02 ± 0.01Wm−2K−1 and −0.02 ± 0.01Wm−2K−1, respectively. Although being one magnitude smaller than the carbon cycle feedback, the weathering feedbacks are comparable in strength to small second-order feedbacks such as methane, fire, or ozone.

Read: Goll, D. S., N. Moosdorf, J. Hartmann, V. Brovkin, 2014: Climate-driven changes in chemical weathering and associated phosphorus release since 1850: Implications for the land carbon balance. Geophys. Res. Lett., 41.

Online: http://onlinelibrary.wiley.com/doi/10.1002/2014GL059471/abstract

Contact: daniel.golldummy@mpimet.mpgdummy2.de

 

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Date issued: 2014-04-29

Investigating High-Resolution AMSR2 Sea Ice Concentrations during the February 2013 Fracture Event in the Beaufort Sea

Sea ice leads are of great importance for the ocean-atmosphere heat exchange. Here we show that the standard sea ice data product is not resolving leads while our new product shows good agreement with high resolution optical images. The new product uses data from the Japanese Advanced Microwave Scanning Radiometer 2 (AMSR2) which was launched in May 2012.

Read: Beitsch, A., L. Kaleschke, S. Kern, 2014: Investigating High-Resolution AMSR2 Sea Ice Concentrations during the February 2013 Fracture Event in the Beaufort Sea. Remote Sens. 6, 3841-3856.

Online: http://www.mdpi.com/2072-4292/6/5/3841

Contact:  lars.kaleschkedummy@zmawdummy2.de

 

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Date issued: 2014-04-22

On the Clausius-Duhem Inequality and Maximum Entropy Production in a Simple Radiating System

A conceptual prototype of a planetary atmosphere is laid down to illuminate some important issues regarding a “climate principle” involving the entropy production rate. Much confusion has been sown since Paltridge conjectured in 1975, on flimsy grounds, that the climate system obeys a principle of maximum entropy production. Following his work, the irreversible nature of the interaction of light and heat radiation with the atmosphere and surface was dealt with in some papers in order to broaden the foundation on which attempts at substantiation of the principle was to be based. The paper in question is designed to shed light on the whole problem. It shows that for the present terrestrial climate the total entropy production rate (including radiation) is close to be maximal, regardless of Earth’s thermal state. On the other hand, for an atmosphere with a weak(er) greenhouse effect, the conclusion no longer holds true.

Read: Pelkowski, J., 2014: On the Clausius-Duhem Inequality and Maximum Entropy Production in a Simple Radiating System. Entropy, 16(4), 2291-2308 .

Online: http://www.mdpi.com/1099-4300/16/4/2291

Contact: joachim.pelkowskidummy@zmawdummy2.de

 

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Date issued: 2014-04-16

Secondary organic aerosol formation during June 2010 in Central Europe: measurements and modelling studies with a mixed thermodynamic-kinetic approach

Until recently secondary organic carbon aerosol (SOA) mass concentrations have been systematically underestimated by three-dimensional atmospheric-chemistry aerosol models. With a newly proposed concept of aging of organic vapours, more realistic model results for organic carbon aerosol mass concentrations can be achieved. Here a case study is presented focusing on Puy-de-Dôme, France in June 2010. The measurements indicate a considerable increase in SOA mass concentration during the measurement campaign, which could be reproduced by modelling using a thermodynamic-kinetic approach for SOA formation.

Read: Langmann,B., K. Sellegri, E. Freney, 2014:  Secondary organic aerosol formation during June 2010 in Central Europe: Measurements and modelling studies with a mixed thermodynamic-kinetic approach. Atmos. Chem. Phys. 14.

Online: http://www.atmos-chem-phys.net/14/3831/2014/acp-14-3831-2014.html

Contact: baerbel.langmanndummy@zmawdummy2.de

 

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Date issued: 2014-04-07

A comparison of satellite- and ground-based measurements of SO2 emissions from Tungurahua volcano, Ecuador

Satellite-measured SO2 mass loadings and ground-based measurements of SO2 emission rate are not directly comparable, with 40% differences between mean emissions reported by each technique from Tungurahua volcano, Ecuador, during late 2007. Numerical simulations of postemission processing and dispersal of Tungurahua’s SO2 emissions enable more effective comparison of ground- and satellite-based SO2 data sets, reducing the difference between them and constraining the impact of plume processing on satellite SO2 observations.

Read: McCormick, B.T. , M. Herzog, J. Yang, M. Edmonds, T. A. Mather, S. A. Carn, S. Hidalgo, and B. Langmann, 2014: A comparison of satellite- and ground-based measurements of SO2 emissions from Tungurahua volcano, Ecuador. J. Geophys. Res. Atmos. 119, 4264–4285.

Online:http://onlinelibrary.wiley.com/doi/10.1002/2013JD019771/abstract;jsessionid=6969A685B821D3027B680581862E0187.f01t02

Contact: baerbel.langmanndummy@zmawdummy2.de

 

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Date issued: 2014-04-01

Asymmetries between along- and across-track velocity spectra from tandem-mission altimetry

Satellite altimetry has proven to be one of the most useful oceanographic datasets, providing a continuous, near-global record of surface geostrophic currents, among other uses. One limitation of observations from a single satellite is the difficulty of estimating the full geostrophic velocity field. The 3-yr Jason-1–Ocean Topography Experiment (TOPEX)/Poseidon tandem mission, with two satellites flying parallel tracks, promised to overcome this limitation. However, the wide track separation severely limits the tandem mission’s resolution and reduces the observed velocity variance. In this paper, the effective spatial filter imposed by the track separation in the wavenumber domain is discussed and two important consequences for any application of the tandem mission velocities are explained.

Read: Cimarron, W., J. Callies, M. G. Scharffenberg, 2014: Asymmetries between Wavenumber Spectra of Along- and Across-Track Velocity from Tandem Mission Altimetry. J. Phys. Oceanogr., 44, 1151–1160.

Online: http://journals.ametsoc.org/doi/full/10.1175/JPO-D-13-0153.1

Contact: martin.scharffenbergdummy@zmawdummy2.de

 

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Date issued: 2014-03-29

Non-exponential return time distributions for vorticity extremes explained by fractional Poisson processes

The serial correlations found for extreme midlatitude cyclones at the storm track exits are explained by fractional Poisson processes (FPPs). We consider extremes in the 850 hPa relative vorticity of the ERA interim reanalysis during boreal winter (DJF) and summer (JJA) seasons. FPPs are based on long-term memory and lead to non-exponential return time distributions. The return time distribution is approximated by a Weibull distribution. The Weibull shape parameter yields a dispersion parameter that agrees with results found for midlatitude cyclones. The memory of the FPP, which is determined by detrended fluctuation analysis, provides an independent estimate for the shape parameter. The analysis exhibits a concise framework of the deviation from Poisson statistics (by a dispersion parameter), non-exponential return times and memory (correlation) on the basis of a single parameter. The results have potential implications for the predictability of extreme cyclones.

Read: Blender, R., C. C. Raible and F. Lunkeit, 2014: Non-exponential return time distributions for vorticity extremes explained by fractional Poisson processes. Quart. J. Roy. Meteorol. Soc., Early view.

Online: http://onlinelibrary.wiley.com/doi/10.1002/qj.2354/pdf

Contact: richard.blenderdummy@uni-hamburgdummy2.de

 

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Date issued: 2014-03-28

How significant is West Antarctic warming?

We re-examine the trend of the observational Byrd temperature record in West Antarctica. We unequivocally show that the traditional trend estimation methods overestimate the anthropogenic minimum trend and underestimate the uncertainty of the trend estimate. This underestimated uncertainty potentially means that the anthropogenic forced trend is much higher than previously thought.

Read:  Bunde, A., J. Ludescher, C. Franzke, and U. Büntgen, 2014: How significant is West Antarctic warming? Nature Geoscience, 7, 246-247.

Online: http://www.nature.com/ngeo/journal/v7/n4/full/ngeo2126.html?WT.ec_id=NGEO-201404

Contact: christian.franzkedummy@uni-hamburgdummy2.de

 

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Date issued: 2014-03-22

The dynamics of the dome at Santiaguito volcano, Guatemala

We measured the velocity of ash particles during vulcanian eruptions at Santiaguito, Guatemala, using a mobile Doppler radar. While examining the data, we found that each eruption consists of several explosions, following each other on a regular basis with a main recurrence period of 3s. Using a simple spring-mass-oscillator, where an impermeable plug (as mass) sits on a compressible, bubbly magma column (spring), we were able to reproduce the inter-eruptive explosion recurrence period of 3s with reasonable parameters for the dimensions of the plug and the amount of gas involved in an eruption.

Read: Scharff, L., M. Hort and A. Gerst, 2014: The dynamics of the dome at Santiaguito volcano, Guatemala. Geophysical Journal International, 197, 926-942.

Online: http://gji.oxfordjournals.org/content/197/2/926.full?sid=02fce8f9-fdf5-4293-8d49-a3d2bdc7658a

Contact: matthias.hortdummy@zmawdummy2.de, lea.scharffdummy@zmawdummy2.de

 

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Date issued: 2014-03-12

Global cities and the production of uneven development  

The paper provides insights on how economic globalization is organized from global cities and contributes thereby to a comprehensive understanding of the processes through which uneven development is produced and sustained.

Read:  Parnreiter, C., 2014 Global cities and the production of uneven development. In: Desai, Vandana/Robert B. Potter (eds.): The Companion to Development Studies. Third edition. Routledge. London, 291-295

Also available at: http://www.lboro.ac.uk/gawc/rb/rb394.html

Contact: parnreiterdummy@geowiss.uni-hamburgdummy2.de

 

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Date issued: 2014-02-27

On the Role of Climate Forcing by Volcanic Sulphate and Volcanic Ash

For geological timescales, it has been suggested that, in addition to the stratospheric climate forcing by volcanic sulphate aerosols, volcanic ash affects climate by modifying the global carbon cycle through iron fertilising the surface ocean and stimulating phytoplankton growth. To trigger future research on the effect of volcanic ash on the climate system via ocean iron fertilisation, this review paper describes the formation processes and atmospheric life cycles of volcanic sulphate and volcanic ash, contrasts their impact on climate, and emphasizes current limitations in our understanding.

Read: Langmann, B., 2014: On the role of climate forcing by volcanic sulphate and volcanic ash. Advances in Meteorology, ID 340123.

Online: www.hindawi.com/journals/amete/2014/340123/

Contact: baerbel.langmanndummy@zmawdummy2.de

 

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Date issued: 2014-02-18

A Nine-Year Climatology of Arctic Sea Ice Lead Orientation and Frequency from AMSR-E

We introduce a new image analysis algorithm to automatically infer sea ice lead positions and orientations. An Arctic-wide time series of lead orientations for winters from 2002 to 2011 was derived from daily satellite observations.

Read: Bröhan, D., L. Kaleschke, 2014: A Nine-Year Climatology of Arctic Sea Ice Lead Orientation and Frequency from AMSR-E. Remote Sens. 6, 1451-1475 .

Online: http://www.mdpi.com/2072-4292/6/2/1451

Contact: lars.kaleschkedummy@zmawdummy2.de,

 

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Date issued: 2014-02-16

SPARE-ICE: Synergistic ice water path from passive operational sensors

Ice water path (IWP, the column amount of frozen hydrometeors in the atmosphere) is an important climate variable. Nevertheless, regarding the climatology of this variable there are currently strong discrepancies between different climate models, partly due to the lack of reliable observations. We have developed a new IWP satellite data product, based on passive microwave and infrared measurements by operational weather satellite, which compares favorably to existing products.

Read: Holl, G., S. Eliasson, J. Mendrok, and S. A. Buehler, 2014: SPARE-ICE: synergistic Ice Water Path from passive operational sensors, J. Geophys. Res., 119 (3), 1504–1523.

Online: http://onlinelibrary.wiley.com/doi/10.1002/2013JD020759/abstract

Contact: stefan.buehler@uni-hamburg.de

Date issued: 2014-04-30

Basic Ecosystem Dynamics in the Red Sea as seen by Sundry Remote Sensing Techniques (book chapter)

Time series of statistical maps of chlorophyll-like pigments concentration, derived from SeaWiFS ocean color data, were used to explore the space and time heterogeneity of algal blooming in the Red Sea. The comparison with concurrent assessments of surface wind speed, derived from QuikSCAT wind scatterometer data, allowed to correlate such heterogeneity with patterns of atmospheric forcing. The general blooming pattern of the Red Sea is reminiscent of the classical
seasonal variation of phytoplankton biomass in sub-tropical basins, specific blooming episodes, particularly in the southern Red Sea, are not driven by the wind field directly.

Read: Barale, V.,  M. Gade (2014): Basic Ecosystem Dynamics in the Red Sea as seen by Sundry Remote Sensing Techniques, in Remote Sensing of the African Seas, V. Barale and M. Gade (Eds), Springer, Heidelberg, 337-355

Online: Print only

Contact: Vittorio Barale, vittorio.barale@jrc.ec.europa.eu; Martin Gade, martin.gade@uni-hamburg.de

 

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Date issued: 2014-04-30

Eddies in the Red Sea as seen by Satellite SAR Imagery (book chapter)

Mesoscale and sub-mesoscale oceanic eddies were observed in approx. 500 Synthetic Aperture Radar (SAR) images of the Red Sea. We found more than 1000 sub-mesoscale eddies, which manifest on SAR imagery either due to local accumulations of surfactant films or due to shear current lines. Those sub-mesoscale eddies seem to be more innumerous in the Red Sea than in other inner seas, presumably due to a relatively deep upper mixed layer in this basin. Together with more than 50 detected meso- and basin-scale eddies they were statistically analyzed in terms of their location, seasonality, diameter, and rotation.

Read: Karimova, S.S., and M. Gade, 2014: Eddies in the Red Sea as seen by Satellite SAR Imagery, in Remote Sensing of the African Seas, V. Barale and M. Gade (Eds), Springer, Heidelberg, 357-378

Online: Print only

Contact: Svetlana Karimova, svetlana.karimova@hzg.de; Martin Gade, martin.gade@uni-hamburg.de

 

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Date issued: 2014-04-16

The surface energy balance and its drivers in a boreal peatland fen of northwestern Russia

In this work we help fill a major regional gap in studies of boreal peatlands and their surface energy balance. Similar studies from northwest Russia simply do not exist. We provide an annual estimate of the energy balance of these important carbon-rich landscapes through half-hourly measurements using the eddy covariance technique, supplemented by site-specific modeling. This work shows the importance of evaporation in the energy balance (taking 70% of net solar radiation) and water balance (exceeding the rainfall to the site). We also demonstrate how simpler models of evaporation can be used in these landscapes, which should assist in their representation in global climate modeling schemes.

Read: Runkle B.R.K., Wille C., Gažovič M., Wilmking M., Kutzbach L. (2014): The surface energy balance and its drivers in a boreal peatland fen of northwestern Russia. Journal of Hydrology, 511, 359–373.

Online: http://dx.doi.org/10.1016/j.jhydrol.2014.01.056

Contact: Benjamin Runkle, benjamin.runkledummy@zmawdummy2.de

 

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Date issued: 2014-03-19

Inorganic Carbon Fluxes in the Inner Elbe Estuary, Germany

We studied the temporal and spatial variations of dissolved inorganic carbon (DIC) fluxes in the inner Elbe estuary based on 18 transects and constructed a budget. We could show that the freshwater part of the Elbe is a hotspot for carbon transformation by using GIS-derived surface areas, isotopic DIC data and modelled pCO2. Annually, the inner Elbe estuary is net heterotrophic and acts as a source for CO2. This reveals that improving water quality does not necessarily imply a strong decline of CO2 emissions. Overall, 20% of total DIC exports are attributed to atmospheric CO2 exchange, while 80% are transported seawards. The study corroborates the anthropogenic impact on carbon fluxes and clearly confirm the necessity to examine the entire estuary including the freshwater part.

Read: Amann T., Weiss A.,Hartman J. (2014): Inorganic Carbon Fluxes in the Inner Elbe Estuary, Germany. Estuaries and Coasts

Online: http://dx.doi.org/10.1007/s12237-014-9785-6

Contact: Thorben Amann, thorben.amann@zmaw.de

 

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Date issued: 2014-03-10

The pace of East African monsoon evolution during the Holocene
African monsoon precipitation experienced a dramatic change in the course of the Holocene. The pace with which the African monsoon shifted from a strong early to middle to a weak late Holocene is controversially debated. On the basis of planktonic foraminiferal Ba/Ca time series from the eastern Mediterranean Sea, we generated a proxy record of Nile River runoff that provides a spatially integrated measure of changes in East African monsoon (EAM) precipitation. The runoff record indicates a markedly gradual middle to late Holocene EAM transition that lasted over 3500 years. The timing and pace of runoff change parallels those of insolation and vegetation changes over the Nile basin, indicating variation of insolation as the main EAM forcing.

Read: Syee Weldeab, Valerie Menke, Gerhard Schmiedl (2014): The pace of East African monsoon evolution during the Holocene. Geophysical Research Letters, 41

Online: http://onlinelibrary.wiley.com/doi/10.1002/2014GL059361/full

Contact: Gerhard Schmiedl, gerhard.schmiedl@uni-hamburg.de; Syee Weldeab, weldeab@geol.ucsb.edu

 

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Date issued: 2014-03-05

Carbon dioxide efficiency of terrestrial enhanced weathering

Enhanced weathering by spreading rock powder on land can contribute to management of atmospheric carbon. We assessed the CO2 budget of this technique. Due to small transport emissions, the main factors affecting the CO2 budget are the rock type (which defines the maximum CO2 sequestration per tonne of rock) and comminution emissions. To sequester 10% of the anthropogenic emissions assumed here with 9.1 Gt/a, 0.9 - 1.7 Gt ultramafic rock would have to be weathered. The socioeconomic and environmental consequences of mining, transporting and weathering that large amount needs more research.

Read: Moosdorf, N., Renforth, P., Hartmann, J., (in press). Carbon dioxide efficiency of terrestrial enhanced weathering. Environmental Science & Technology

Online: http://pubs.acs.org/doi/abs/10.1021/es4052022

Contact: Contact: Nils Moosdorf, nils.moosdorf@zmaw.de, Tel. 040 428386683; Jens Hartmann, jens.hartmann@zmaw.de, Tel: 040 428386686

 

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Date issued: 2014-03-01

Multi-frequency SAR data help improving the monitoring of intertidal flats on the German North Sea coast

More than 200 Synthetic Aperture Radar (SAR) images of exposed intertidal flats on the German North Sea coast have been analyzed with respect to signatures of bivalves (mussels and oysters), macrophytes and vegetation (seagrass). In order to detect and to identify various types of Wadden Sea surfaces and their spatial and temporal variability we took advantage of the different acquisition times, radar frequencies and polarizations. Moreover, remnants of historical landuse, in areas that were lost to the sea during major storm surges in the 14th and 17th centuries, were detected from space.

Read: Gade, M., S. Melchionna, K. Stelzer and J. Kohlus, 2014: Multi-Frequency SAR Data Help Improving the Monitoring of Intertidal Flats on the German North Sea Coast, Estuar. Coast. Shelf Sci., 140, 32-42

Online: http://dx.doi.org/10.1016/j.ecss.2014.01.007

Contact: Martin Gade, martin.gade@uni-hamburg.de

 

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Date issued: 2014-02-12

Dynamical system properties of an axisymmetric convective tropical cyclone model
We investigated the dynamical system behaviour of tropical cyclones and their potential intensity in the convection-resolving model HURMOD. The model results point to the existence of bifurcations with the sea surface temperature representing the bifurcation parameter. The sea surface temperature range, within which the system exhibits bifurcation points, is found to be sensitive to environmental relative humidity and tropospheric temperature stratification. This indicates that the observed sea surface temperature threshold for cyclogenesis is shifting in response to climate change.

Read: Daria Schönemann, Thomas Frisius (2014): Dynamical system properties of an axisymmetric convective tropical cyclone model. Tellus A, 66, 22456

Online: http://dx.doi.org/10.3402/tellusa.v66.22456

Contact: Daria Schönemann, daria.schoenemann@zmaw.de

 

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Date issued: 2014-01-18

Silica fluxes in the inner Elbe Estuary, Germany

Between 2009 and 2013, we investigated the silica cycle in the Elbe estuary. The analysis revealed that the Elbe Estuary is a source for dissolved silica (DSi), contradicting the general assumption of estuaries being a sink for DSi, and a strong sink for biogenic silica (BSi). We discussed major drivers of the Si cycle and the connected anthropogenic impact. Furthermore, we proposed a method to reconstruct BSi values from particulate organic carbon (POC) measurements from a long-term monitoring programme.

Read: Thorben Amann, Andreas Weiss, Jens Hartmann (2014): Silica fluxes in the inner Elbe Estuary, Germany. Biogeochemistry 118, 1-3, pp 389-412

Online: http://dx.doi.org/10.1007/s10533-013-9940-3

Contact: Thorben Amann, thorben.amann@zmaw.de

 

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Date issued: 2013-12-31

Late Holocene rupture history of the Ventas de Zafarraya Fault (Southern Spain)
One of the most destructive earthquakes on the Iberian Peninsula (Ms 6.7) occurred in 1884 along the Ventas de Zafarraya Fault. We built three trenches and used sedimentology, microstratigraphy, high-resolution sub-surface Ground-Penetrating-Radar and radiocarbon dating to characterize the faulting history in the last 10 ky. Four major events (Ms around 6.5 ± 0.5) were revealed and the mean slip rate during the Holocene is estimated to be on the order of 0.3 to 0.45 mm/y. One major conclusion is that the recurrence period for “characteristic” earthquakes along the VZF is on the order of 2000 years.

Read: Grützner, C., Ruano, P., Jabaloy, A., Galindo-Zaldívar, J., Becker-Heidmann, P., Sanz de Galdeano, C., Rudersdorf, A., Reicherter, K. (2013): Late Holocene rupture history of the Ventas de Zafarraya Fault (Southern Spain). Cuaternario y Geomorfología , 27 (3-4): 5-32

Online: http://recyt.fecyt.es/index.php/CUGEO/article/view/23517/11747

Contact: Peter Becker-Heidmann, p.becker-heidmann@uni-hamburg.de

Cost-effectiveness analysis of water-saving irrigation technologies based on climate change response: A case study of China

We investigated the mitigation and adaptation potential of water-saving irrigation, and the cost-effectiveness of water-saving irrigation based climate change mitigation and adaptation. The analysis shows the economic and environmental benefits of adapting to climate change by using water-saving devices on the agricultural sector. The paper also develops a proposal of water-saving irrigation policies according to the cost-effectiveness analysis.


Read: Xiaoxia Zou, Yu’e Li, Roger Cremades, Qingzhu Gao, Yunfan Wan, Xiaobo Qin: " Cost-effectiveness analysis of water-saving irrigation technologies based on climate change response: A case study of China", Agricultural Water Management, Volume 129/November 2013, doi: 10.1016/j.agwat.2013.07.004
Online:
http://www.sciencedirect.com/science/article/pii/S0378377413001856
Contact: Roger Cremades, roger.cremades@zmaw.de


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Evidence of parallel denitrification and nitrite oxidation in the ODZ of the Arabian Sea from paired stable isotopes of nitrate and nitrite

The Arabian Sea is one of the three major oceanic nitrogen sinks and its oxygen deficient zone (ODZ) extends from about 100 m to 1200 m water depth. We investigated and quantified nitrogen turnover processes in the ODZ by using paired stable isotopic ratios of nitrate and nitrite. Nitrate reduction and denitrification are restricted to a zone between 100 m and 400 m and dominate only in the core of this layer. At the upper and lower margin of the denitrification zone a significant amount of initially reduced nitrite is returned to the nitrate pool by nitrification. A box model shows that 25% of the produced nitrite is reoxidised to nitrate while 40% is further denitrified to dinitrogen gas. Below 400 m water depth, we found no indications for denitrification although oxygen conditions are still conducive. The lower margin of the denitrification zone is probably determined by the paucity of organic substrate rather than by oxygen conditions.

 

Read: Birgit Gaye, Birgit Nagel, Kirstin Dähnke, Tim Rixen, Kay-Christian Emeis: Evidence of parallel denitrification and nitrite oxidation in the ODZ of the Arabian Sea from paired stable isotopes of nitrate and nitrite. Global Biogeochemical Cycles, 27, doi:10.1002/2011GB004115.

Online: http://onlinelibrary.wiley.com/doi/10.1002/2011GB004115/pdf

Contact: Dr. Birgit Gaye, birgit.gaye@zmaw.de, 040/428387088; Birgit Nagel, Birgit.Nagel@hzg.de, 04152/872379

 

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Amino acid composition and delta15N of suspended matter in the Arabian Sea: implications for organic matter sources and degradation

Sedimentation in the ocean is fed by large fast sinking aggregates produced in the surface mixed layer. These sinking particles have often been proposed to interact by disaggregation and scavenging with a pool of slowly sinking fine suspended matter with long oceanic residence time. Our investigations of amino acid composition and stable nitrogen isotopic ratios of suspended matter and sinking particles suggest that the exchange between the two particle types is insignificant. We propose that the observed divergence of sinking and suspended particle composition with water depth is due to the exchange of suspended matter with the dissolved organic matter pool. The role of this process in global element cycles needs to be assessed.

 

Read: B. Gaye, B. Nagel, K. Dähnke, T. Rixen, N. Lahajnar, K.-C. Emeis: Amino acid composition and delta15N of suspended matter in the Arabian Sea: implications for organic matter sources and degradation. Biogeosciences, 10, 7689-7702, doi:10.5194/bg-10-7689-2013, 2013.

Online: http://www.biogeosciences.net/10/7689/2013/bg-10-7689-2013.pdf

Contact: Dr. Birgit Gaye, birgit.gaye@zmaw.de, 040/428387088; Birgit Nagel, Birgit.Nageldummy@hzgdummy2.de,  04152/872379

 

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HAVSTOVAN NR.: 13-13 TECHNICAL REPORT “Monitoring the flow of Atlantic water through the Faroe-Shetland Channel”

This report presents results from an experiment within the EU FP7 THOR and NACLIM projects (www.naclim.eu) to investigate whether future monitoring of the Atlantic water transport through the Faroe-Shetland Channel might be more efficiently achieved on another section than the traditional Munken-Fair Isle section. The new section is less affected by meso-scale activity and narrower, allowing better horizontal resolution of the mooring array, but the experiment revealed that moving to the new section involved other drawbacks. Based on the conclusions of this report, we recommend that future in situ monitoring in the channel is re-focused.

 

Read: Bogi Hansen, Karin M. H. Larsen, Hjálmar Hátún, Regin Kristiansen, Ebba Mortensen, Barbara Berx, Toby Sherwin, Svein Østerhus, Detlef Quadfasel, Kerstin Jochumsen. HAVSTOVAN NR.: 13-13, Technical Report

Online: http://www.hav.fo/PDF/Ritgerdir/2013/TecRep1313.pdf

Contact: Detlef Quadfasel, detlef.quadfasel@zmaw.de; Bogi Hansen, Bogihan@hav.fo