DISPERSION MODELING IN NORTHRHINE-WESTPHALIA - REGULATIONS, GUIDELINES AND PRAGMATIC APPROACHES

In Germany the only regulation concerning dispersion modelling is foun d in Annex C of the Technical Instructions on Air Quality Control (TA Luft). It prescribes a Gaussian plume model but does not consider feat ures such as wet deposition, dynamic plume rise and transport in struc tured terrain. Several VDI Guidelines have been formulated to harmoniz e handling of those features. However, concerning dispersion modelling in the vicinity of a source where the influence of buildings has to b e taken into account, no general proposal has been made. As there are several models to calculate flow and concentration fields in the vicin ity of buildings, first steps have been made in the State of Northrhin e-Westphalia to find a pragmatic approach for using these models to de termine annual means and percentiles. Thereby the number of different meteorological situations to be considered has to be reduced. The resu lting coarser classification of wind speed, wind direction and stabili ty classes must be based on the available meteorological frequency dis tributions.