Intercalibration activities at CIMSS in preparation for the GOES-R era

High spectral resolution polar-orbiting satellite instruments, such as the Atmospheric InfraRed Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI), can be used to intercalibrate infrared measurements from the global system of operational geostationary imagers. The international community of satellite operators, through the World Meteorological Organization, has recognized a need for an improved quantitative assessment of satellite calibration for applications such as climate monitoring and has formed an international committee to coordinate a Global Satellite-Based Intercalibration System (GSICS). In addition to climate monitoring and sensor comparisons, intercalibration provides satellite operators with feedback on instrument operation and response to changes implemented from the ground. Comparisons between geostationary imagers and high spectral resolution polar orbiters have provided an improved understanding of calibration performance of all the operational geostationary imagers; CIMSS is engaged in performing a retrospective analysis of all GOES Imagers using the historical records of both IASI and AIRS. A very important time to assess the calibration accuracy of a geostationary instrument is during its post-launch test (PLT) period. For example, the GOES-13 PLT intercomparison with AIRS ultimately resulted in a new spectral response function for the 13.3 micrometer band on the Imager. The NOAA science GOES-14 PLT will be held in December 2009. CIMSS is engaged in these activities as part of the preparation work for cal/val activities being planned for the GOES-R era with respect to the Advanced Baseline Imager (ABI).