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Integration and Assimilation of Meteorological (ECMWF) Aerosol Estimates into Sen2Cor Atmospheric Correction

Sen2Cor is a Level-2A processor designed to correct Sentinel-2 Level-1C products from the effects of the atmosphere in order to deliver a Level-2A surface reflectance product. A key-parameter for accurate atmospheric correction is the knowledge of the spatially and temporally very variable aerosol content of the atmosphere The multi-spectral instrument on board Sentinel-2 has the appropriate spectral bands to derive the aerosol optical thickness (AOT) of the atmosphere, provided the image contains reference areas of known reflectance behavior, preferably dense dark vegetation (DDV). If the granule contains no DDV pixels, a fallback solution is required. The former solution was to generate an AOT map based on the start visibility set in the configuration file. In this updated Sen2Cor version, meteorological AOT estimates are retrieved from ECMWF ftp server and pre-processed. The integration and assimilation of ECMWF aerosol estimates into Sen2Cor atmospheric correction is described and recent validation results are presented.