CRG Glaciology (2010-2012)

The cryosphere is a key element of the climate system. On the one hand it is very climate-sensitive thereby providing a rapid response to climate change; on the other hand, changes in the polar cryosphere will have a strong positive feedback with far reaching implications. The CliSAP Research Group Glaciology improved numerical models of dynamical ice sheets, ice shelves and ice streams, including the investigation of processes essential for reliable predictions. This work was essential for improving existing climate models and also for estimating future sea level change.

CRG Glaciology existed until 08/2012.

Objectives

Numerical ice modeling is an interplay of different components: the level of approximation, grid resolution and structure, the description of processes and the condition of a specific site. They determine the complexity and the scale-dependence of the modeling approach. Consequently, the work program in CliSAP-2 will be divided into the following three fields:

(1) Application of existing models to selected, but diverse, cases to test their skill in simulating present day dynamics and robustness and to determine the factors governing their uncertainties. This includes application and extension of models using different numerical techniques, different levels of approximation and the assessment of the potential of their coupling. This working field is thus the numerical perspective of ice modeling and its scale dependence. The benefit of this field is a basis for future model development.

(2) Investigation of glaciological processes, which requires data analysis, theoretical and numerical modeling. Additionally to the physical description of the processes, parameterizations will be developed, applicable for coarser grids. We focus on the following: basal sliding, subglacial hydrological processes, calving and ice shelf break-up. The outcome in this field is a contribution to fundamental glaciological research.

(3) Studies in specific key regions. The scope of this part is to answer questions about the stability of ice masses, the mass balance of ice sheets and hence their contributions to sea level rise. Thus, the acceleration of outlet glaciers of Greenland and ice streams, e.g. Pine Island, grounding line dynamics and the response of ice streams and outlet glaciers to retreating ice fronts and internal feedback algorithms are subjects of our studies. The dynamics of the Antarctic and Greenland ice sheets with a focus on areas with active subglacial water systems and vulnerable ice shelves, e.g. Wilkins, will complete this field. The output of this component will potentially be of relevance for IPCC reports and the assessment of recent changes in the Arctic and Antarctic.

Naturally, these three fields are connected. This will be complemented by the development of concepts for future approaches using hybrid resolution grids and adaptive complexity. This comprises concepts for the decision making in numerical models about the appropriate level of complexity.