Explicit Methods for Stii Odes from Atmospheric Chemistry

The subject of research is the numerical integration of atmospheric chemical kinetics systems. The application lies in the study of air pollution, modelled by atmospheric chemistry-transport problems. This application puts high demands on the eeciency of the stii solver. Three explicit methods are discussed and compared for a selected chemical kinetics system which is representative for the state of the art. The rst and the second method are of the explicit QSSA type and the third is based on the two-step backward diierentiation formula, combined with Gauss-Seidel iteration to approximately solve the implicitly deened solution. This also renders the method explicit. In the comparison the two-step method comes out best. Note: This paper is one of a series on the development of algorithms for long range transport air pollution models (CWI projects EUSMOG and CIRK).