A Mass Balance of SO2 Over Baden-Württemberg During the Tulla Experiment

The TULLA experiment was carried out during March 1985 over Baden- Wurttemberg. One of the aims of the experiment was the determination of a mass balance of SO2 over Baden-Wurttemberg. The results of the SO2 measurements in different levels along the boundaries of Baden- Wurttemberg on March 25, 1985 are used to determine the corresponding mass balance. To compare the measured concentrations along the flight patterns with model results, calculations with a three dimensional diffusion model have been performed. The flew field and the field of the dispersion coefficients are determined by a non-hydrostatic mesoscale model, which calculates these fields using the meteorological data measured in Stuttgart on that day. The emissions of SO2, available as hourly averages at a 1 km x 1 km grid, and the SO2-flux into Baden-Wurttemberg have been taken into account as sources. The concentration of SO2along the flight pattern derived fron measurements and from the model are in good agreement. Although the influences of orography on the flow field are very strong the maximum and minimum concentrations at the outflow boundaries are located at the same positions.