Investigation of radiative tranfer model effect on radiometric inter-calibration of GPM sounder channels

This paper concerns the development of an improved algorithm for the inter-satellite radiometric calibration (XCAL) for microwave sounders in support of NASA's Global Precipitation Mission (GPM). This research extends previous XCAL work by incorporating different radiative transfer models for atmospheric water vapor absorption (namely; Rosenkranz and MonoRTM) to assess the robustness of the CFRSL “double difference” technique for sounder X-CAL. This paper presents new results of the GPM Microwave Imager (GMI) comparisons with the SAPHIR sounder on the Megha-Tropique satellite. Using a one-year GMI observations, we present a statistical analysis of SAPHIR radiometric biases performed over time and viewing geometry (SAPHIR scan angles).