The research group focuses on understanding processes in various climate-related dynamical systems. We model the atmosphere, the ocean and the climate as a dynamical system. Due to the mathematical complexity of the earth system and our own limited resources we find it necessary to consider only subsystems in which external influences are prescribed by means of exogenous parameters. The earth system is itself a subsystem of the universe, depending as it does upon external influences like irradiation from the sun. As a matter of modelling economy it is unavoidable to idealize and simplify the dynamical subsystems. Some processes cannot be resolved and must be “parameterized” by other, measurable system variables. It is in this spirit that we analyze tropical cyclones, the ocean circulation, simple climate models with radiative transfer and the hydrologic cycle of the global climate system.
Climate relevant processes are multifaceted and highly structured so that only a complex equation set can describe them with a large degree of accuracy.
The solutions can numerically determined only by high performance computers. They are suitable to emulate reality but often do not contribute to the understanding. A better understanding can be achieved by simplified and idealized models. Such models often stimulate the formulation of new theoretical concepts and new directions of thought.
Simplifying and understanding complex physical processes
The CliSAP research group “Dynamical Systems” adopts idealized models of simple and intermediate complexity in order to attain a better and deeper comprehension of the physical processes.
In this spirit the research group is currently concerned with the following projects:
- Tropical cyclone system dynamics
- Irreversible processes in phase transitions and radiative transfer
- Nonlocality of tropical cyclone activity in the climate system
- EOF reduction of ocean circulation models
- Dynamical Core Model Intercomparison Project (DCMIP)
- 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, 3659-3679. doi:10.1175/JAS-D-15-0336.1.
- Frisius, T. (2015). What controls the size of a tropical cyclone? Investigations with an axisymmetric model. Quarterly Journal of the Royal Meteorological Society, 141(691), 2457-2470. doi:10.1002/qj.2537.
- Pelkowski, J. (2014). On the Clausius-Duhem Inequality and Maximum Entropy Production in a Simple Radiating System. ENTROPY, 16(4), 2291-2308. doi:10.3390/e16042291.
- Schönemann, D., & Frisius, T. (2014). Dynamical system properties of an axisymmetric convective tropical cyclone model. Tellus Series A-Dynamic Meteorology and Oceanography, 66: 22456. doi:10.3402/tellusa.v66.22456.