Eulerian modeling of photochemical pollutants over the Swiss Plateau and control strategy analysis

A three-dimensional Eulerian photochemical model was applied to the Swiss Plateau for the 28–30 July 1993 period to follow the evolution of ozone and other photochemical oxidants. The results of the three-day base case simulation showed good to excellent agreement across the region not only for ozone, nitrogen oxide, nitrogen dioxide and carbon monoxide, but also for other pollutants such as peroxyacetyl nitrate and hydrogen peroxide. The effect of the boundary and initial conditions were found to be negligible. The next step was to determine quantitatively the effects of differing levels of ROG and NOx controls on O3 and other photo-oxidant levels. Twelve calculations combining different precursor emission levels were performed in order to simulate the effects of controls on ozone peaks, as well as exposure to the various pollutants. The results suggest that reducing NOx emissions, on a percentage basis, is more effective for lowering both ozone peaks and exposure than is reducing ROG. PAN responds in a similar fashion to ozone. Given the model performance, and the fewer limitations involved in using three-dimensional Eulerian models than other methods, this is a powerful tool for conducting further control strategy evaluations.