Five years of aircraft measurements of air pollution in an industrialized region in Eastern Germany

Between 1990 and 1994, 19 flights were performed with a highly instrumented research aircraft in and around an industrialized region in eastern Germany to study horizontal transport and temporal trends of air pollutants after the time of German unification. Besides the dolphin flight path for vertical screening of the boundary layer, a mapping flight path at 150 m above ground was employed. The meteorological conditions severely limited the interpretability of the data sets in many cases. We found those data that were gained during conditions with a stable boundary layer can not be utilized for emission flux computations or trend analyses. Also, in cases with a neutrally stratified or convective boundary layer, the data sets were of complex structure which hindered the application of parametric statistical tools. Therefore, any meaningful emission fluxes could not be decuded from data sets that were measured in short distance to the emission sources. Trend analyses with non-parametric tests indicate that the flux densities of SO2 decreased both on the upwind and downwind sides of our area of investigation. Although no trend could be identified for nitrogen oxides, it seems that the relative contribution of nitrogen oxides to primary air pollution has been gaining weight at the expense of sulfur dioxide in eastern Germany in the early 1990s.