Global Precipitation Measurement (GPM) is an international satellite mission to provide next-generation observations of rain and snow worldwide every three hours. NASA and the Japanese Aerospace Exploration Agency (JAXA) will launch a “Core” satellite carrying advanced instruments that will set a new standard for precipitation measurements from space. The data they provide will be used to unify precipitation measurements made by an international network of partner satellites to quantify when, where, and how much it rains or snows around the world.
The GPM mission will help advance our understanding of Earth's water and energy cycles, improve the forecasting of extreme events that cause natural disasters, and extend current capabilities of using satellite precipitation information to directly benefit society.
GPM: Building on TRMM’s Legacy
The Tropical Rainfall Measuring Mission (TRMM), launched in 1997, measures moderate and heavy rainfall in the tropics. TRMM has shown the importance of taking measurements at different times of day to improve observations of weather systems and real-time monitoring of hurricanes. The GPM Core Observatory will continue this sampling strategy, but will extend the observations to higher latitudes, covering the globe from the Antarctic Circle to the Arctic Circle.
The design of the GPM Core Observatory is an advancement of TRMM’s highly successful rain-sensing package, which uses an active radar capable of providing information on precipitation particles, layer-by-layer, within clouds, and a passive microwave imager capable of sensing the total precipitation within all cloud layers. Since light rain and falling snow account for a significant fraction of precipitation occurrence in middle and high latitudes, the GPM instruments extend the capabilities of the TRMM sensors to detect falling snow, measure light rain, and provide, for the first time, quantitative estimates of microphysical properties of precipitation particles.
GPM Science and Applications
Water is fundamental to life on Earth. Knowing where and how much rain and snow falls globally is vital to understanding how weather and climate impact both our environment and Earth’s water and energy cycles, including effects on agriculture, fresh water availability, and responses to natural disasters. Since rainfall and snowfall vary greatly from place to place and over time, satellites can provide more uniform observations of rain and snow around the globe than ground instruments, especially in areas where surface measurements are difficult. GPM’s next-generation global precipitation data will lead to scientific advances and societal benefits in the following areas: