COMPARATIVE-ANALYSIS OF CHEMICAL-REACTION MECHANISMS FOR PHOTOCHEMICAL SMOG

Six chemical reaction mechanisms for photochemical smog are analyzed to determine why, under identical conditions, they predict different maximum ozone concentrations. Answers to previously inaccessible questions such as the relative contributions of individual organic species to photochemical ozone formation are obtained. Based on the results of the analysis, specific aspects are identified of each mechanism that are responsible for the discrepancies with other mechanisms and with an explicit mechanism based on the latest understanding of atmospheric chemistry. For each mechanism critical areas are identified that when altered bring the predictions of the various mechanisms into much closer agreement. Thus, it is identified why the predictions of the mechanisms are different, and research efforts are recommended that are needed to eliminate many of the discrepancies.