Odour dispersion modelling with Lagrangian and Gaussian models

The Lagrange particle diffusion model LASAT and the Gaussian Austrian Odour Dispersion Model AODM are used to calculate direction-dependent separation distances around livestock farms. As the method has been published already in several papers, the focus is here on the differences of the results due to model physics. With both models, the same peak-to-mean algorithm is used to calculate short-term peak concentrations relevant for odour dispersion. For both models, the same emission and meteorological data, but model-specific atmospheric stability classes have been used. The estimate of atmospheric stability is obtained from three-axis ultrasonic anemometers using the standard deviations of the three wind components and the Obukhov stability parameter. Separation distances are determined for two odour impact criteria, namely exceedence probabilities of 3 and 8 %, each in combination with the odour threshold of 1 ouE/m. The results will be presented and discussed for two sites with very different topographical surroundings.