A typical model of global atmospheric chemistry contains a chemical reaction scheme with 70-100 species and about 300 reactions. A corresponding number of chemical equations must be solved for each of ~250,000 model grid cells at each time step using iterative solution procedures. Furthermore, the model contains parameterizations of physical processes such as advection, diffusion, convection, dry deposition, and the washout in and below clouds. Various model components (atmospheric physics, atmospheric chemistry, ocean dynamics, ocean biogeochemistry, land surface processes) are coupled together to form a comprehensive Earth System Model.
In the global modeling group of IEK-8 we contribute to the development of the global chemistry climate model ECHAM-HAMMOZ. This model is based on the ECHAM general circulation model and contains th eaerosol module HAM and the atmospheric chemistry module MOZART, which calculates tropospheric and stratospheric trace gas concentrations. ECHAM-HAMMOZ can be used for longer-term climate simulations as well as for shorter runs, for example in order to interpret field campaign data.