Preliminary Case Study of Geostationary IR Sounding Data from FY-4A GIIRS

A hyperspectral Infrared sounder, the Geostationary Interferometric Infrared Sounder (GIIRS), is pre-operational aboard the Chinese Fengyun-4A satellite. The GIIRS has an spectral resolution in the thermal infrared which matches the JPSS CrIS sensors on S-NPP and NOAA-20. It is the first geostationary interferometer that provides continuous soundings of temperature and humidity which has been successfully launched into Earth orbit. The GIIRS radiance data is currently in preliminary processing but is expected to become widely available later this year. GIIRS will obtain hourly vertical data of the atmosphere which is valuable for near real-time tracking of the pre-convective storm environment. In this study, comparisons are made between GIIRS-derived vertical profiles of temperature and humidity and local observational data from coincident radiosonde launch sites, e.g. at Shanghai. The GIIRS soundings and those derived using SNPP CrIS are compared using the CSPP DR algorithm and the operational NOAA NUCAPS ATMS/CrIS retrievals. This activity is part of an assessment performed at SSEC/CIMSS of the characteristics of the GIIRS radiances and the suitability of assimilation into NWP models.