Global models of the atmosphere are traditionally used in weather forecasting and climate research. Global numerical weather prediction (NWP) models predict the temporal development of the state of the atmosphere within a period of one or two weeks on the basis of an accurate as possible analysis of the initial conditions. The spatial resolution can be as high as the available computer capacity permits.
Climate research model simulations have to cover much longer periods of several decades. This can only be realized at the expense of the spatial resolution. The initial conditions are less important than an appropriate representation of the essential parts of the Earth system, e.g. the oceans, the chemosphere, the cryosphere and the biosphere. In addition, trace species (e.g. ozone or aerosols) are incorporated as interactive components of the climate models as they act on the radiation budget of the climate system while their distribution is modified by the state of the atmosphere.
At the Institute of Atmospheric Physics the modular model system MESSy (Modular Earth Submodel System) is being developed and maintained. The global model EMAC (ECHAM/MESSy atmospheric chemistry model), which comprises the atmosphere model ECHAM, has been based on MESSy. EMAC has been configured and applied in numerous studies. In addition the institute is involved in the development of the new German model ICON.