AN ESTIMATION OF THE AVERAGE NOX CONTAMINATION OF SOUTHERN BAVARIA BY REGIONAL EMITTERS

A climatology of flow patterns and NO(x) concentrations for Southern Bavaria is determined by use of a mesoscale model. Emissions of the main regional emitters of NO(X) are prescribed in the model. A simple parameterization of the chemical processes is applied. The climatologIes are obtained by performing model simulations of typical dispersion situations and weighting the results according to the frequency of their occurrence. The computed NO(x) and wind statistics agree satisfactorily with the available observations. Thus, the modelled NO(x) climatology is believed to be realistic. During daytime, NO(x) is mainly concentrated above the emission areas, whereas at night the NO(x) distribution is more uniform and the contamination of the surroundings increases. The contamination during the winter half-year is about twice that of summer half-year. The highest average annual NO(x) concentration of 64 ppb is found in the region of Munich. The calculated mean NO(x) distribution is useful for supplementing the sparse observational data. Additionally, the model simulations allow the determination of the contributions of emitters to the NO(x) contamination at any given location.