Convective dispersion modelling utilising acoustic sounder information

Abstract

Recently developed air pollution dispersion models for convective conditions are briefly reviewed in terms both of their potential for incorporating the information from current acoustic sounder technology and of their success in comparison with laboratory and field studies. The routine production of vertical velocity histograms and estimates of eddy dissipation rates by a turbulence sounder allows a first order incorporation of site-specific information into relatively simple descriptions of chimney plume behaviour. Experimental results from two sites are presented and compared with the predictions of a preferred dispersion model. Acoustic sounder and ground-level sulphur dioxide measurements have enabled a preliminary assessment to be made of the capacity to predict ground-level concentrations around Gladstone, a sub-tropical coastal power station. Sounder profiles suggest that the vertical turbulence in a seabreeze is proportionally less near the coast than further inland. The model can successfully include this finding. A site further inland at Stanwell, known for its topographically induced net downdraft, provided a further test of such a method. Satisfactory agreement with tracer gas studies carried out on the site has given some confidence in the estimates of maximum shortterm ground-level concentrations and of the frequency of occurrence of concentrations anywhere in the neighbourhood of the proposed power station. Methods of incorporating inversion penetration, wind shear and tower data into the preferred model are presented.