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

摘要

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 bandswith a spatial resolution of 3 km. In this work the Aerosol Optical Thickness (AOT) retrieval over land using SEVIRIdata is presented. AOT at 0.55 μm is estimated minimizing the difference between measured and computed radiances inthe visible channel centered at 0.6 μm by means Look-Up Tables (LUT) obtained using 6S radiative transfer code. The0.6 μm surface reflectance has been computed using different procedures based on SEVIRI channels 3 and 4 centeredrespectively around 1.6 and 3.9 μm. For the 0.6 μm surface reflectance retrieval using the 1.6 μm procedure, themeasurements of five automatic sun-photometers of the Aerosols Robotic Network (AERONET) located in theMediterranean area (Avignon, Laegeren, Modena, Rome and Lecce) has been used. The procedures show encouragingresults in case of 1.6 μm procedure retrieval and the inadequacy of 3.9 μm 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 comparedwith MODIS retrieval.