A comparison of model photochemical ozone formation potential with observed regional scale ozone formation during a photochemical episode over the United Kingdom in April 1987

Abstract

A photochemical trajectory model has been employed to calculate the maximum potential for ozone generation in air parcels passing over the U.K. during a photochemical pollution episode in April 1987. In all, 11 trajectories have been studied and the model results compared against an objective analysis of the integrated ozone generation based on the observations reported from the U.K. Department of the Environment ground level O 3network. There is apparently good correlation between the observed O 3formation and the model O 3formation potential although the latter overestimates the former by a factor of about 2.8. The solar illumination conditions employed in the photochemical trajectory model may have caused this overestimation, since the model is formulated for O 3control strategy assessment and simulates the ‘worst case’ situation likely to give the maximum potential for secondary pollutant formation. In addition to the model results for O 3, a wide range of primary and secondary pollutant concentrations from the model were examined, together with the influence of precursor pollutant emissions.