THE CHEMISTRY OF THE POLLUTED ATMOSPHERE OVER EUROPE - SIMULATIONS AND SENSITIVITY STUDIES WITH A REGIONAL CHEMISTRY-TRANSPORT-MODEL

A model environment has been established, which allows an estimation o f the influence of global climate change on the chemistry of the pollu ted atmosphere over Europe. For this purpose the regional chemistry-tr ansport-model of the EURAD-system has been modified and made adaptable for input data from a regional climate model, which is nested in a gl obal atmospheric circulation model. Thus, the dynamical aspect of a po ssible global temperature increase as well as enhanced water vapour co ncentrations and background concentrations of carbon monoxide and meth ane can be considered. By substituting the meteorological driver model the main problems arise from different vertical grids and physical pa rameterization Schemes. In particular, the parameterization of cloud p rocesses has to be checked to avoid inconsistencies between the chemis try-transport-model and its meteorological driver model. As the length of a simulation period is mainly limited by the large amount of compu ter, time spent for the determination of chemical transformation rates , the gas-phase chemistry module has been optimized concerning compute r time and numerical stability. For validation studies of the new mode l system two episodic simulations were investigated, one for a summer photo-oxidants period in July 1990, the other one for January 1991. (C ) 1997 Elsevier Science Ltd.