CliSAP successfully finished in 2018. Climate research continues in the Cluster of Excellence "CLICCS".


The ICSM series (Interaction Coefficient Spectral Model) provide a set of spectral models, that simulate two-dimensional nondivergent flows in a rectangular model domain.The model fields are expanded in a double Fourier-series so that the model equations form a dynamical system for the Fourier coefficients. The wave numbers at which the expansion is truncated can be chosen freely. Therefore, it is convenient to compare results of low and high oder models for the same physical system.


This model solves the so-called barotropic vorticity equation for a channel flow (periodic in east-west or x-direction). With ICSM_BARO we can for example investigate shear flow instabilities. The ICSM_BARO also includes the Beta-effect which stems from the northward increase of the Coriolis parameter. With this effect the model is capable to simulate Rossby waves.


The model ICSM_OCE is based upon ICSM_BARO but it includes lateral boundaries and wind stress forcing. The model is capable of simulating the wind-driven circulation in a rectangular basin.


The Boussinesq approximated equations for two-dimensional viscous and heat conducting fluids are solved by ICSM_RB. The model can, therefore, simulate Rayleigh-Benard convection rolls. ICSM_RB reduces to the well-know Lorenz model of a Chaotic attractor when a low order configuation with only one wavenumber in horizontal direction and two wavenumbers in vertical direction are selected. ICSM_RB is also suitable for the investigation of internal gravity waves by prescribing a stable stratification.


This is an extension of ICSM_RB to a model for the thermohaline overturning circulation. It includes an additional equation for salinity as well as sources for heat and fresh-water. The boundary conditions are in contrast to ICSM_RB insulating. With the model it is possible to reproduce a bifurcation diagram demonstrating transions from thermally-driven to salinity-driven circulations and also the transition from 2-cell to 1-cell circulation patterns.


ICSM_2L is a quasi-geostrophic two-layer model after Phillips (1951). It simulates a channel flow of two fluids of different density lying upon each other. The upper layer exhibits in comparison to the lower layer a smaller density. The quasi-geostrophic appriximation results for a small Rossby number which is assumed to be given for the simulated flow. The model is suitable to investigate baroclinic instability and to simulate life cycles of baroclinic waves.

- Peer-reviewed articles that use results of ICSM simulations:

  • Gálfi, V. M., T Bódai and V. Lucarini, 2017: Convergence of extreme value statistics in a two-layer quasi-geostrophic atmospheric model. Complexity, 2017, 20 pp. doi:10.1155/2017/5340858
  • Schubert, S. and V. Lucarini, 2016: Dynamical analysis of blocking events: spatial and temporal fluctuations of covariant Lyapunov vectors. Quarterly Journal of the Royal Meteorological Society, 142, 2143–2158. doi: 10.1002/qj.2808
  • Schubert, S. and V. Lucarini, 2015: Covariant Lyapunov vectors of a quasi-geostrophic baroclinic model: analysis of instabilities and feedbacks. Quarterly Journal of the Royal Meteorological Society, 141, 3040–3055. doi: 10.1002/qj.2588
  • Frisius, T., 2003: On the development of a cyclone-anticyclone asymmetry within a growing baroclinic wave. Journal of the Atmospheric Sciences, 60, 2887-2906. doi: 10.1175/1520-0469(2003)060<2887:TDOACA>2.0.CO;2
  • Frisius, T., 1999: A simple model for the baroclinic life cycle of meridionally elongated eddies in uniform shear. Journal of the Atmospheric Sciences, 56, 3508-3519. doi: 10.1175/1520-0469(1999)056<3508:ASMFTB>2.0.CO;2
  • Frisius, T., 1998: A mechanism for the barotropic equilibration of baroclinic waves. Journal of the Atmospheric Sciences, 55, 2918-2936.doi: 10.1175/1520-0469(1998)055<2918:AMFTBE>2.0.CO;2
Sequentially ordered fields of streamfunction (thick isolines) and potential vorticity (thin isolines) of the lower layer as simulated by ICSM_2L. The left, middle and right columns show the baroclinic wave development for different flow symmetries. The i