Author(s)

M. van Loon

Abstract

Fast and efficient solution methods for ozone chemistry M. van Loon Center for Mathematics and Computer Science, Department NW, ABSTRACT Two special-purpose solvers for chemical kinetics problems, the QSSA me- thod and TWOSTEP, together with the state-of-the-art stiff solver VODE, provided with sparse matrix routines, are considered for application in an atmospheric model. Of all three methods a short description is given. A comparison is made for a chemical model describing (parametrized) ozone chemistry. The code TWOSTEP turns out to be a good alternative for the QSSA solver as regards accuracy and to outperform VODE with respect to computation time for accuracies near 1%. INTRODUCTION Atmospheric models are computationally very expensive. Usually the com- putational work is dominated by the numerical treatment of systems of ordinary differential equations (ODEs) describing the chemical transforma- tions. One reason is that these systems are stiff due to the presen

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