Normalization and Calibration of Geostationary Satellite Radiances for the international Satellite Cloud Climatology Project

Abstract

Procedures are described for normalizing the radiometric calibration of image radiances obtained from the suite of geostationary weather satellites that contributed data to the international Satellite Cloud Climatology Project. The key step is comparison of coincident and collocated measurements made by each satellite and the concurrent Advanced Very High Resolution Radiometer (AVHRR) on the ?afternoon? NOAA polar-orbiting weather satellite at the same viewing geometry. The results of this comparison allow transfer of the AVHRR absolute calibration, which has been established over the whole series, to the radiometers on the geostationary satellites. Results are given for Meteosat-2, Metcosat-3, and Meteosat-4, for GOES-5, GOES-6, and GOES-7, for GMS-2, GMS-3, and GMS-4 and for Insat-IB, The relative stability of the calibrations of these radiance data is estimated to be within ±3%, the uncertainty of the absolute calibrations is estimated to be less than 10%. The remaining uncertainties are at least two times smaller than for the original radiance data.