Modelling air pollution transport and deposition

This paper gives an outline of the principles that are used to model atmospheric pollution. It discusses relevant ideas of the atmospheric boundary layer, its stability, and how the mixing varies with atmospheric stability. The author considers examples of modelling ranging from: (1) forecasts of urban air quality using a box model; (2) plume calculations using a Gaussian formulation and the more recent UK-ADMS model; (3) photochemical ozone arriving in the UK from Europe modelled by a chemical trajectory box model; (4) nuclear accident dispersion modelling using many particle random walk modelling (the NAME model); and (5) application of the NAME model to sulphur pollution and eventually to ozone formation chemistry. The author begins with dispersion in the atmospheric boundary layer, then considers deposition before looking at examples of models. Since the boundary layer is the lowest part of the atmosphere nearest the ground, it is strongly influenced by temperature changes at the surface, and by the drag on the flow. (7 pages)