Remote sensing of aerosol optical depth over central Europe from MSG-SEVIRI data and accuracy assessment with ground-based AERONET measurements

In this study, the remote sensing of aerosol optical depth ( tau(a)) from the geostationary Meteosat Second Generation ( MSG) Spinning Enhanced Visible and Infrared Imager ( SEVIRI) is demonstrated. The proposed method is based on the analysis of a time series of SEVIRI's 0.6 mu m channel images. Top-of-atmosphere reflectance is precorrected for the effect of atmospheric gases and a background aerosol amount. Subsequently, surface reflectance for each pixel is estimated by determining its lowest precorrected reflectance within the observed time period for each satellite observation time of the day. The resulting diurnal surface reflectance curve in combination with the radiative transfer code SMAC are finally used to derive ta. This approach is applied to SEVIRI subscenes of central Europe ( 40.8 - 51.3 degrees N, 0.3 degrees W - 19.9 degrees E) from August 2004, daily acquired between 0612 and 1712 UTC in intervals of 15 min. SEVIRI tau(a) are related to Aerosol Robotic Network ( AERONET) Sun photometer measurements from nine sites. About 3200 instantaneous SEVIRI and Sun photometer tau(a) are compared. An overall correlation of 0.9 and a root mean square error of 0.08 are obtained. Further, the spatial distribution of SEVIRI tau(a) maps for August 2004 represent expectable features like higher concentrations in industrialized regions or lower loading in higher altitudes. It is concluded that the described method is able to provide an estimate of tau(a) from MSG-SEVIRI data. Such aerosol maps of high temporal frequency could be of interest to atmospheric related sciences, e. g., to track aerosol particle transport.