An Aerosol Modelling Study of Winter and Summer Periods in Switzerland

In this paper, we discuss the application of the MM5/CAMx model system under winter and summer conditions in 2006 over the complex terrain of Switzerland. The focus of the study is on the formation and transport of particulate matter (PM). Both measurements and model results indicate that the main components of the winter aerosols are particulate nitrate and organic aerosols. The meteorological model seems to predict the meteorological parameters reasonably well except during periods with low-wind speed. The results suggest that organic aerosols are the most dominant species in summer and they are mostly secondary. In general, CAMx predicts the concentrations of inorganic aerosols correctly while organic aerosols are underestimated. Possible causes for the underestimation might be the lack of wood-burning emissions and missing processes leading to secondary organic aerosols like oligomerization which are not yet treated by the model.