EVALUATION OF A NUMBER OF CHEMICAL MECHANISMS FOR THEIR APPLICATION IN MODELS DESCRIBING THE FORMATION OF PHOTOCHEMICAL OZONE IN EUROPE

A series of 24 chemical mechanisms from the literature are compared against each other using harmonized emissions, photolysis rate coefficients for simple inorganic chemistry and life cycle data for ozone, PAN and H2O2. The evaluation sought to understand the impact of parameterizing hydrocarbon oxidation on the peak concentrations of photochemically-generated secondary pollutants. Only seven of the 24 chemical mechanisms gave peak concentrations of ozone, PAN and H2O2 simultaneously in their respective central ranges. PAN and H2O2 were generally calculated with a much lower precision compared to ozone. Only 11 mechanisms out of 24 gave responses to both 50% hydrocarbons and NOx emissions controls in their respective central bands. The lack of coordinated ozone, PAN and hydrogen peroxide measurements across Europe currently limits the adequacy of model comparisons and hence the confidence which may be placed in assessments of likely impacts of future control strategies. © 1990.