Abstract :
The equations of atmospheric chemistry are very stiff and represent the major computational obstacle in the simulation of the chemical and physical processes in the atmosphere. This paper compares two examples of “preconditioned time differencing”, a technique for constructing cheap time stepping schemes for chemical kinetic ODE systems by eliminating much of the matrix algebra associated with the usual implicit calculation. These preconditioned schemes are also compared with a well known implementation of the popular backward differentiation formulas, and are shown to be a viable alternative to these fully implicit BDF methods applied to chemical kinetics systems. Tests are carried out on a small 2 species system, a box model problem, and a full three-dimensional chemical-radiative-transport model.
