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).