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We test the reliability of an inverse model to estimate the amount of mass released instantaneously by a source of pollutant in a turbulent boundary layer. To that purpose we use wind tunnel experiments simulating the dispersion of puffs due to the impulsive release of pollutant. For each of these emissions we recorded time dependent signals at fixed receptors. These single signals have been used as input data for an inverse dispersion model in order to evaluate its error in estimating the real emission of pollutant. The inversion has been also performed using the ensemble average of the 100 signals as input data. The comparison of both approaches allows us to discuss the reliability of an atmospheric dispersion inverse model in real situations.

We use a Lagrangian stochastic micromixing model to predict the concentration fluctuations of a continuous release in a neutral boundary layer. We present the computational algorithm that implements the interaction by exchange with the conditional mean model and we compare the numerical solutions with the experimental values in order to evaluate the reliability of the model. The influence of the source size on the concentration probability density function in the near and far-field is discussed and some shortcomings of the model are pointed out.

Lagrangian dispersion models require estimates of the local dissipation rate ( e ) of turbulent kinetic energy ( k ). In this study, we evaluate the sensitivity of a Lagrangian model to different estimates of e in simulating passive scalar dispersion in a turbulent boundary layer over a rough surface. Two different estimates of e are used to simulate pollutant dispersion emitted by a linear elevated source with a Lagrangian model which integrates a macromixing and a micromixing scheme. Comparison between numerical and experimental results allows us to discuss the performance of the model and to define its sensitivity to e .

Dispersion in urban areas is determined by transport and mixing processes within the street network and ventilation into the external atmosphere. In order to improve the understanding of the exchange mechanisms within the urban canopy, wind tunnel and numerical investigations have been performed on two idealised typical urban configurations, the street intersection and the square. The numerical simulations were compared to the experimental values, in order to evaluate the reliability of the numerical approach in simulating local flow patterns and study the influence of the geometrical layout on mass and momentum exchange mechanisms.