1st Leibniz MMS Days - Abstract

Wolke, Ralf

Coupled time-integration of atmospheric chemistry-transport processes by using multirate implicit-explicit schemes

The application of suitable time integration schemes is especially important for highly dynamical problems like atmospheric chemistry-transport processes. Usually, classical time integrators take the same time step over the com-plete domain and for all components. Consequently, the model regions and the components with the strictest time step restrictions dictate this global time step. Opposed to this, multirate schemes are employed to adapt the time step locally, so that slower components take longer and fewer time steps, which can reduce the computational costs substantially. In the paper, a new class of time integration schemes is proposed which combines the multirate approach with implicit-explicit (IMEX) methods. These schemes are applied for block-structured grids with different horizontal resolutions as well as the coupling between aerosol dynamical and gas phase chemical processes in the chemistry-transport model COSMO-MUSCAT.