Performance of the US EPA's Climatological Dispersion Model in calculating ambient sulphur dioxide concentrations in London

Abstract

The performance of the US EPA's Climatological Dispersion Model as a means of estimating ground-level winter sulphur dioxide concentrations in London has been assessed by use of historical (1975/1976) meteorological, air quality and emission data. A correlation coefficient of 0·86 was achieved between observed and model-calculated concentrations for the eighty-two monitoring locations in operation at that time. Over 40% of the calculated concentrations were within ±10% of the observed values, and over 70% within ±20%. The sensitivity of the model's predictions to various input parameters was examined. Source emission rates and atmospheric mixing heights were found to be the parameters to which the model is most sensitive. Systematic errors in stability and wind speed categories of the order of one ‘class’ were also found significantly to affect the model's predictions.