Variational sensitivity analysis of a photochemical smog mechanism

The variational method of sensitivity analysis is applied to a recent chemical kinetic mechanism for photochemical smog. It is demonstrated that the variational method is capable of readily handling a large mechanism. The analysis can be applied to a single chemical species or to an arbitrarily large group of species contained in an objective function. Examples of the use of different objective functions are given. The variational method provides temporally distributed sensitivity coefficients. Therefore, the results are presented as a time-dependent ranking of reactions in orderof decreasing importance with respect to the objective function species. This ranking permits the time-dependent relative influence of each reaction to be readily determined by inspection. Particular attention is paid to reactions governing daytime O₃ formation and nighttime NO₃ and HONO formation.