COMPARISON OF 6 GAUSSIAN DISPERSION MODELS USED FOR REGULATORY PURPOSES IN DIFFERENT COUNTRIES OF THE EU

The environmental impact of industrial emissions from stacks of 30 m, 80 m and 150 m have been compared using five Gaussian models that are routinely used for regulatory purposes in one or more member states of the EU. The models are: IFDM (Belgium), PLUIMPLUS (the Netherlands), AUSTAL86 (Germany), OML (Denmark) and ISCST2 (several countries). All models are run with the same meteorological input data for the year 19 85. The observations along the 120 m high meteorological tower in Mel, completed with the synoptic observations in Kleine Brogel and the rad io soundings of Brussels, are used. The comparison is based on the yea rly average, the 98-percentile of the hourly averages and the maximum hourly average concentrations. The largest values for these parameters differ by a factor of up to 3. The spatial distribution of the calcul ated impact can also be very different for the considered models. Thes e differences are almost entirely due to the use of different turbulen ce typing schemes and the associated dispersion parameters. A sixth mo del studied in this paper is IMMPROG (Switzerland, Belgium). Although this model is based on the same principles as the AUSTAL86 model, the differences between the models are considerable.