Intercomparison of Lagrangian stochastic models based on two different PDFs

In this work two different Lagrangian stochastic models for convective turb ulence are compared and tested against the Indianapolis dataset. The two mo dels are based on the generalized Langevin equation, whose coefficients are solutions of the Fokker-Planck equation. The first model uses the bi-Gauss ian probability density function (PDF) following Luhar and Britter (1989) a nd the second one, proposed by us (Ferrero and Anfossi, 1998), is based on the Gram-Charlier PDF. Both models are able to take into account up to the third order moment of the wind velocity fluctuation vertical component and make use of the Gaussian assumption in the horizontal directions. Basically the two models here considered are different versions of our stochastic di spersion model for flat terrain, LAMBDA. This means that plume rise is take n into account and that the correct boundary conditions are used. The resul ts obtained are presented and their differences discussed.