Developments in flow and dispersion modelling in the atmospheric boundary layer

Recent developments in concepts , models and parameterisations of the eddy structure and statistics of abl turbulence are reviewed , with particular mention on their variability and low frequency features. Models , laboratory and field experiments on orographic and urban effects indicate the need for new parameterisations , including coriolis and unsteady effects even on scales at 10km or less.Dispersion modelling from point sources has developed to account for the effects of these more complex features of the flow and turbulence , including their effects on non-gaussian profiles , effects of micromixing in stable conditions, split plumes,concentration fluctuations , diurnal unsteadiness ,and chemical reactions.