Prediction of total oxides of nitrogen and nitrogen dioxide concentrationsin 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 generati on 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 predi ct concentrations from emission sources in Greater London. Predictions have been compared with observed data at four locations, two locations in Centr al 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 assi st in the comparison of model predictions with monitored data. Although no absolute significance can be attached to the numerical values of these meas ures, taken cumulatively, some conclusions regarding the emissions inventor y data and the models' performance can be made. The applicability of the mo del of atmospheric chemistry used in this study to calculate the concentrat ions of nitrogen dioxide is appraised and a comparison has been made with c oncentrations of nitrogen dioxide predicted from oxides of nitrogen using e mpirical relationships. (C) 1999 Elsevier Science Ltd. All rights reserved.