Radiometric inter-calibration of satellite microwave humidity sounders using the GPM Microwave Imager

Inter-calibration of microwave atmospheric sounder channels using the GPM Microwave Imager (GMI) is a challenging task. Previously the Double Difference (DD) inter-satellite radiometer calibration has been used successfully for - satellite microwave conical scanning imagers and recently it has been applied to the microwave cross track scanners as well. However, in this paper, the inter-calibration between conical scanner and cross track scanner is investigated. Here, the sounder channels on the Special Sensor Microwave Imager/Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) are used as a proxy for GMI to cross-calibrate with the corresponding channels of Sondeur Atmosphérique du Profil d´Humidité Intertropicale par Radiométrie (SAPHIR) on the Megha-Tropiques satellite.