Numerical Simulation of Aqueous-Phase Atmospheric Models: Use of a Nonautonomous Rosenbrock Method

Rafik Djouad, Bruno Sportisse and Nicole Audiffren

Accepted for publication in Atmospheric Environment, September 2001.

We present in this article an efficient numerical solver for the time integration of atmospheric multiphase chemical kinetics. This solver is based on a second-order Rosenbrock scheme, that has been proposed by Verwer et al \cite{verwer7}. for gas-phase chemical kinetics. We show that the stiff time dependence of cloudy events (through liquid water content) has to be solved by the numerical scheme and a non-autonomous version has to be used. We benchmark our non-autonomous {\sc ros2} scheme with the classical {\sc lsode} solver for two kinetic schemes. For detailed schemes such as {\sc radm2}, the speed-up is of magnitude 5 for the same accuracy.