EXPLICIT METHODS FOR STIFF ODES FROM ATMOSPHERIC CHEMISTRY

The subject of research is the numerical integration of atmospheric ch emical kinetics systems. The application lies in the study of air poll ution, modelled by atmospheric chemistry-transport problems. This appl ication puts high demands on the efficiency of the stiff solver. Three explicit methods are discussed and compared for a selected chemical k inetics system which is representative for the state of the art. The f irst and the second method are of the explicit QSSA type and the third is based on the two-step backward differentiation formula, combined w ith Gauss-Seidel iteration to approximately solve the implicitly defin ed solution. This also renders the method explicit. In the comparison, the two-step method comes out best.