An aerosol optical thickness retrieval algorithm for Meteosat Second Generation (MSG) data over land: application to the Mediterranean area

The Spinning Enhanced Visible And Infra Red Imager (SEVIRI) radiometer, on board on Meteosat Second Generation(MSG) geostationary satellite, collects, each 15 minutes, images of the underneath part of the globe in 12 spectral bands with a spatial resolution of 3 km. In this work the Aerosol Optical Thickness (AOT) retrieval over land using SEVIRI data is presented. AOT at 0.55 mu m is estimated minimizing the difference between measured and computed radiances in the visible channel centered at 0.6 mu m by means Look-Up Tables (LUT) obtained using 6S radiative transfer code. The 0.6 pm surface reflectance has been computed using different procedures based on SEVIRI channels 3 and 4 centered respectively around 1.6 and 3.9 mu m. For the 0.6 pm surface reflectance retrieval using the 1.6 mu m procedure, the measurements of five automatic sun-photometers of the Aerosols Robotic Network (AERONET) located in the Mediterranean area (Avignon, Laegeren, Modena, Rome and Lecce) has been used. The procedures show encouraging results in case of 1.6 pm procedure retrieval and the inadequacy of 3.9 pm procedure. An AOT map of the Po Valley (Italy), obtained from an MSG image taken during a typical winter polluted day, is shown in the paper and compared with MODIS retrieval.