Modeling results of atmospheric dispersion of NO2 in an urban area using METI-LIS and comparison with coincident mobile DOAS measurements

Synergetic use of in-situ measurements, remote sensing observations and model simulations can provide valuable information about atmospheric chemistry and air quality. In this work we present for the first time a qualitative comparison between modeled NO2 concentrations at ground level using dispersion model METI-LIS and tropospheric NO2 columns obtained by mobile DOAS technique. Experimental and modeling results are presented for a Romanian city, Braila (45.26 degrees N, 27.95 degrees E). In-situ observations of NO2 and meteorological data from four ground stations belonging to the local environmental agency were used to predict the concentration of NO2 at ground level by atmospheric dispersion modeling on two days when mobile DOAS measurements were available. The mobile DOAS observations were carried out using a UV-VIS spectrometer mounted on board a car. The tropospheric Vertical Column Density (VCD) of NO2 is deduced from DOAS observations. The VCD was obtained using complementary ground and space observations. The correlation between model and DOAS observations is described by a correlation coefficient of 0.33. Also, model results based on averaged in-situ measurements for a period of 5 years (2008-2012) are used for an overview of the background NO2 evolution in time and space for the selected urban area.