MODELING THE IMPACT OF NOX OR HYDROCARBON CONTROL ON PHOTOCHEMICAL OZONE IN EUROPE

Current understanding of the fast photochemical balance of the sunlit boundary layer points to there being a simple relationship between the rate of ozone production and the rate of oxidation of NOx. Observational evidence is presented to show that such a relationship indeed describes what is likely to be happening during summertime photochemical episodes in Europe. Photochemical trajectory models are able to reproduce a similar relationship and this allows some confidence to be given to their ability to assess ozone control strategies. Hydrocarbon or NOx emission controls are found to reduce episode peak ozone concentrations downwind of major European source areas. However, in the more remote areas of Europe, only NOx emission controls appear to be justified.