Upgrade of the DAUMOD atmospheric dispersion model to estimate urban background NO2 concentrations

Abstract

Ambient concentrations of nitrogen dioxide (NO2) resulting from the emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in an urban area, may cause adverse impacts on the human health and the natural environment if they exceed the air quality standards. The evaluation of NO2 can be achieved through the application of air quality models including photochemical reactions. DAUMOD is a simple urban scale atmospheric dispersion model which was originally developed to estimate urban background concentrations of inert species. In order to allow the estimation of NO2 concentrations in an urban atmosphere, the DAUMOD model has been recently coupled to the Generic Reaction Set (GRS), a simplified photochemical scheme. This work presents the development of the DAUMOD-GRS model and its first application in the city of Buenos Aires considering high resolution area source NOx and VOCs emissions recently obtained for the area. Estimated hourly NO2 concentrations are compared with observations from a campaign carried out at a green open area within the city in winter 2001. Results show a good model performance, with NMSE=0.49, FA2=0.676 and FB=-0.097. DAUMOD-GRS is applied to obtain the spatial distribution of annual NO2 concentrations in the city. The maximum value is 36 ppb, indicating that annual NO2 concentrations in Buenos Aires are below the Air Quality Standard (53 ppb). In addition, hourly ozone concentrations estimated by DAMOD-GRS are compared with observed values, giving NMSE=0.38, FA2=0.684 and FB=-0.225.