SLIMCAT (and related TOMCAT) is a global three-dimensional (3-D) off-line chemical transport model (CTM) which is developed and maintained at the University of Leeds. The model uses winds and temperatures from meteorological analyses (e.g. from the European Centre for Medium-Range Weather Forecasts) to specify the atmospheric transport and temperatures. The distinctive feature about SLIMCAT is that vertical motion in isentropic coordinates is determined by calculated heating rates. The model then calculates the chemical composition of the upper troposphere and stratosphere based on the chemical scheme and inputs such as solar fluxes and trace gas emissions. The model has the option of detailed chemical scheme(s) for the stratosphere and troposphere.

The model can be used to simulate the past and current atmosphere, to help interpret observations, and to diagnose the extent of environmental issues such as stratospheric ozone depletion or tropospheric pollution. INVICAT, the inverse version of TOMCAT, is used to derive surface emission fluxes. TCOM data products use machine learning to combine TOMCAT output and satellite observations.

A number of datasets on CEDA have been produced with the SLIMCAT model (and related TOMCAT, INVICAT, TCOM). Further details of the specific model set-up are provided in dataset descriptions.