Linking the GRS photochemical scheme with the DAUMOD urban atmospheric dispersion model

The DAUMOD model is a simple urban scale atmospheric dispersion model which was originally developed to estimate inert air pollutant ground-level background concentrations resulting from a great number of area emission sources. The model has been tested against observations from Buenos Aires and different cities of Europe and the US, and has been extensively used during the past two decades to study the air pollution related to NOx species in the city of Buenos Aires and surrounding areas. The Generic Reaction Set (GRS) constitutes a simplified scheme of the most complete photochemical mechanisms. Due to its simplicity and its ability to reproduce the interactions between NO, NO2 and O3 at urban scale, the GRS has been widely adopted in air quality assessment studies. In this work, we present the coupling of the DAUMOD model with the GRS. The developed coupled model DAUMOD-GRS is applied to estimate the ground-level concentrations of NO2 and O3 resulting from high resolution (1h, 1km) NOx and VOC emissions in the Metropolitan Area of Buenos Aires (MABA). Modelled hourly concentrations are tested against observed values at several sites. The statistical measures obtained are satisfactory. The comparison of model estimations with air quality data measured at twenty sites across the MABA shows that for NO2 (N=2909), the normalised mean square error (NMSE) is 0.83, the fraction of two within observations (FA2) is 0.575, and the fractional bias (FB) is 0.034; while for O3 (N=3100), NMSE=0.21, FA2=0.821 and FB=-0.066.