Boundary layer high order concentration statistics

The higher order concentration statistcs of a passive tracer in a turbulent Boundary Layer are evaluated by a Fluctuating Plume model. A non stationary Lagrangian Stochastic Model is used to determine the joint evolution of the barycentre of a cloud and a time-dependent filter assures that only the correct portion of the turbulent kinetik energy is considered. The instantaneous dispersion of the plume around its barycentre is parametrized following the inertial range scaling and the concentration of the passive tracer is determined following Gifford (1959). The model has been applied to two different Boundary Layers: a convective boundary layer and a plant canopy. Concentration Fluctuations, Skewness and Kurtosis are presented, in particular their dependence from the concentration PDF relative to the Plume barycentre position inside the Boundary Layer is investigated. Two different PDF are taken in to account a Gaussian PDF and a Skewed PDF. The comparison is shown and discussed.