Global Precipitation Measurement (GPM) Microwave Imager (GMI) After Four Years On-Orbit

The Global Precipitation Measurement (GPM) Microwave Imager (GMI) launched aboard the GPM Core Observatory as a joint mission between the National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA) has operated with high stability for four years. The noise equivalent delta temperature (NEDT) for each channel has be exceptionally stable. Non-linearity as measured using the 4-point calibration technique has been shown to be stable within +/-0.02K. Calibration features such as the hot load, cold sky reflector and main reflector coating continue to provide high quality calibration with no discernable degradation of performance. The on-orbit trending of calibration is facilitated using the on-board noise sources. The antenna was calibrated on-orbit to within 0.25K 1-sigma over the ocean.