AN OPERATIONAL DISPERSION MODEL FOR PREDICTING POLLUTION FROM A ROAD

We present here a mathematical model for predicting dispersion of poll ution from a road, for use in a regulatory context. The model includes an emission model, treatment of the meteorological time series, a dis persion model, statistical analysis of the computed time series of con centrations and a graphical Windows-based user interface. The dispersi on model is based on a partly analytic solution of the Gaussian diffus ion equation for a finite line source. It allows for any wind directio n with respect to the road. Dispersion parameters are evaluated using stability data produced by a meteorological preprocessing model, based on a Monin-Obukhov-type boundary layer scaling. The chemical transfor mation is modelled by using the discrete parcel method. it contains th e basic reactions of nitrogen oxides, oxygen and ozone. The validity o f the presented analytic solution has been tested against a more detai led numerical model; the results show that it can be used with confide nce.