3-DIMENSIONAL VERSION OF THE DANISH EULERIAN MODEL

The two-dimensional Danish Eulerian Model has been. developed during t he 80'ies. More than 70 chemical reactions (some of them photochemical ) are involved in the model. The space domain of the model covers the whole of Europe. It has been discretized by using a (32 x 32) equidist ant spatial grid. The concentrations and the species calculated by the model were compared both with measurements taken over land and with m easurements taken over sea. The model has also been run by using finer grids; as, for example, a (96 x 96) grid. The experiments indicated t hat in general the model calculates rather reliable results. However, it is also clear that the results might be improved if a three-dimensi onal version of the model is developed. Three-dimensional air pollutio n models are very time-consuming. Therefore the development of a relia ble three-dimensional version of an air pollution model is a very chal lenging task. The efforts to solve some of the numerical problems aris ing during the development of a large three-dimensional air pollution model (with non-linear chemical reactions) will be discussed in this p aper.