Prediction of total oxides of nitrogen and nitrogen dioxide concentrations in a large urban area using a new generation urban scale dispersion model with integral chemistry model

This paper describes the use of urban emission inventory data and an urban scale dispersion model (ADMS-Urban) to calculate concentrations of NOx and NO2 in London. The dispersion model used in this study is a second generation Gaussian dispersion model which is characterised by the use of boundary layer similarity profiles to parameterise the variation of turbulence with height within the boundary layer. The model has an integral chemistry model which is used to predict concentrations of nitrogen dioxide and ozone. The paper examines the performance of the integrated modelling system to predict concentrations from emission sources in Greater London. Predictions have been compared with observed data at four locations, two locations in Central London and two in East London. Predicted concentrations for a summer and winter period have been calculated and modelled and measured times series data have been compared. Statistical analyses have been carried out to assist in the comparison of model predictions with monitored data. Although no absolute significance can be attached to the numerical values of these measures, taken cumulatively, some conclusions regarding the emissions inventory data and the models' performance can be made. The applicability of the model of atmospheric chemistry used in this study to calculate the concentrations of nitrogen dioxide is appraised and a comparison has been made with concentrations of nitrogen dioxide predicted from oxides of nitrogen using empirical relationships. (C) 1999 Elsevier Science Ltd. All rights reserved.