EULERIAN MODELING OF PHOTOCHEMICAL POLLUTANTS OVER THE SWISS PLATEAU AND CONTROL STRATEGY ANALYSIS

A three-dimensional Eulerian photochemical model was applied to the Sw iss Plateau for the 28-30 July 1993 period to follow the evolution of ozone and other photochemical oxidants. The results of the three-day b ase case simulation showed good to excellent agreement across the regi on not only for ozone, nitrogen oxide, nitrogen dioxide and carbon mon oxide, but also for other pollutants such as peroxyacetyl nitrate and hydrogen peroxide. The effect of the boundary and initial conditions w ere found to be negligible. The next step was to determine quantitativ ely the effects of differing levels of ROG and NOx controls on O-3 and other photo-oxidant levels. Twelve calculations combining different p recursor emission levels were performed in order to simulate the effec ts of controls on ozone peaks, as well as exposure to the various poll utants. The results suggest that reducing NOx emissions, on a percenta ge basis, is more effective for lowering both ozone peaks and exposure than is reducing ROG. PAN responds in a similar fashion to ozone. Giv en the model performance, and the fewer limitations involved in using three-dimensional Eulerian models than other methods, this is a powerf ul tool for conducting further control strategy evaluations.