Modeling of the transport and diffusion of a tracer in the Freiburg-Schauinsland area

In June 1996, the Schauinsland Ozone Precursor Experiment (SLOPE) was perfo rmed in the area of Freiburg-Schauinsland (Germany). A major objective of t his experiment was to investigate the behavior of ozone and its precursors of the city plume of Freiburg on the way from Freiburg to Schauinsland [Vol z-Thomas et nl., this issue]. Meteorological [Kalthoff et nl., this issue] and chemical measurements [Patz er nl., this issue; Kolahgar er al., this i ssue] were carried out at several stations along the expected transport pat h between Freiburg and Schauinsland. In order to separate the contribution of transport and diffusion from that of chemical reaction, to calculate the transport time and dilution factor, the inert tracer SF, was released at t he beginning of the transport path [Kalthoff et al., this issue; M. Mollman n-Coers et al., unpublished data, 1999 (hereinafter referred to as M99)]. T he results from the model calculations were first compared with the observa tions at different measurement sites. Then the calculations were used to pr ovide interpretation support with regard to the mesoscale meteorological ph enomena observed. Finally, they delivered explanations for the observed tem poral development and spatial distribution of the tracer concentrations bet ween Freiburg and Schauinsland.