Modelling concentration fluctuations for operational purposes

We investigated the two first moments of the concentration distribution from a point source release thanks to wind tunnel measurements. The results were analysed with the statistical model from Yee et al. (1994). This model requires two parameters related to the larger scale velocity fluctuations and to the concentration variability due to smaller scale fluctuations respectively. A robust semi-empirical relation for the intensity of the concentration fluctuations was derived. Such a relation can be combined with the mean concentration estimates provided by a Gaussian puff model to compute the standard deviation of pollutant concentration.