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

In June 1996, the Schauinsland Ozone Precursor Experiment (SLOPE) was performed in the area of Freiburg-Schauinsland (Germany). A major objective of this experiment was to investigate the behavior of ozone and its precursors of the city plume of Freiburg on the way from Freiburg to Schauinsland [Volz-Thomas et nl., this issue]. Meteorological [Kalthoff et nl., this issue] and chemical measurements [Patz er nl., this issue; Kolahgar er al., this issue] were carried out at several stations along the expected transport path 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tracer SF, was released at the beginning of the transport path [Kalthoff et al., this issue; M. Mollmann-Coers et al., unpublished data, 1999 (hereinafter referred to as M99)]. The results from the model calculations were first compared with the observations at different measurement sites. Then the calculations were used to provide interpretation support with regard to the mesoscale meteorological phenomena observed. Finally, they delivered explanations for the observed temporal development and spatial distribution of the tracer concentrations between Freiburg and Schauinsland.