Global precipitation measurement microwave imager (GMI) On-orbit calibration

The refining of the GMI calibration on-orbit has involved a number of activities to directly measure key calibration parameters. The activities have included 1) using the backup calibration from the noise diodes to direction measure stability-related terms, 2) inter-comparison with other satellites, 3) observatory attitude maneuvers, and 4) long-term averaging of cold counts. The resulting GMI absolute calibration accuracy is about 0.25K 1-sigma bias over the ocean.