GPM GMI First Light

Narration: Dan Gallagher


The new GPM Microwave Imager, or GMI, produced unprecedented images of an extra-tropical cyclone in the Northwest Pacific Ocean, east of Japan, on March 10, 2014. The GMI measures the natural energy radiated by different precipitation in the form of brightness temperatures. The GMI produces a critical reference standard, which unifies all the member satellites of the GPM Constellation. The instrument has 13 channels, four more than onboard TRMM, and this greater sensitivity allows GPM to measure a greater variety of precipitation type and intensity. Each channel has a frequency range that can detect a different type of precipitation. The lower frequencies for moderate to heavy rain, the middle frequencies for a mix of rain and snow, and the higher frequencies for falling snow and ice. Scientific algorithms then translate the GMI's brightness temperature data into more meaningful products, such as rain rates. Because GPM's coverage extends beyond the tropics, measuring storms like these in the mid- and high-latitudes will improve and expand the global view of precipitation.