A MATRIX APPROXIMATION TO LARGE SCALE PHOTOCHEMICAL MODEL CALCULATIONS

The QSSA model for photochemical reactions in the atmosphere is simulated by a limited system of linear differential equations which can be solved analytically. This permits the use of large time-steps, and the computer time may be reduced by a factor of more than 500, while retaining an overall accuracy which is compatible with other uncertainties and inaccuracies of the total problem.