A one-dimensional climate-chemistry model is used to simulate atmospheric chemistry for different meteorological and chemical conditions and at different geographical locations. The necessary initial and boundary conditions have been adopted from two global models, the European Centre Hamburg Model 4 (ECHAM4) (meteorology) and the Tracer Model 3 (TM3) (chemistry). Both global models use analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) as input; the climate model ECHAM4 is "nudged" towards these analyses. The chemical scheme of TM3 is used, which is a modified version of the Carbon Bond Mechanism 4 (CBM-4). The one-dimensional model includes a parametrization for horizontal segregation effects that occur on a sub-grid scale for mesoscale and global chemistry models. Horizontal segregation can occur when the chemical lifetime of species is relatively short compared to the turbulent mixing time. Such segregation might have a significant impact on the evolution of the mean concentration of chemical species. We present an assessment of the importance of horizontal segregation effects for global atmospheric chemistry modelling
Symposium on Interdisciplinary Issues in Atmospheric Chemistry