How does GPM improve water resource prediction and benefit agriculture?

Both water resource managers and the agricultural community need to know the amount, distribution, timing and onset of seasonal rainfall to prepare for freshwater shortages and forecast crop yields. By providing four-dimensional measurements of space-time variability of global precipitation, GPM allows for a better understanding of precipitation systems, water cycle variability, and freshwater availability to predict changes in freshwater supply and assess crop productivity.

How does GPM improve weather forecasting?

The increased sensitivity of the Dual-frequency Precipitation Radar (DPR) and the high-frequency channels on the GPM Microwave Imager (GMI) enables GPM to improve forecasting by estimating light rain and falling snow outside the tropics, even in the winter seasons, over areas which other satellites and ground sensors are unable to measure. These advanced measurements extend current capabilities in monitoring and predicting hurricanes and other extreme weather events, as well as contributing to improve forecasting for floods, landslides, and droughts.

Why was the GMI Off-Nadir angle of 48.5° chosen?

At the start of the modern passive microwave age, the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) was designed to give an Earth Incidence angle (EIA) around 53°. The design parameters for SSMI were generated by Jim Hollinger, at NRL at the time, and meant to address several Earth science variables, not just precipitation. For EIAs around 53°, the roughness component of the wind speed signal is nearly zero in vertical polarization.