International Global Precipitation Measurement Mission (GPM) Data Goes Public

On March 17, 2014 the Global Precipitation Measurement (GPM) mission's Core Observatory flew over the East coast's last snow storm of the 2013-2014 winter season.

This was also one of the first major snow storms observed by GPM shortly after it was launched on February 27, 2014.

The GPM Core Observatory carries two instruments that show the location and intensity of rain and snow, which defines a crucial part of the storm structure - and how it will behave.

The GPM Microwave Imager sees through the tops of clouds to observe how much and where precipitation occurs, and the Dual-frequency Precipitation Radar observes precise details of precipitation in 3-dimensions.

For forecasters, GPM's microwave and radar data are part of the toolbox of satellite data, including other low Earth orbit and geostationary satellites, that they use to monitor tropical cyclones and hurricanes.

One of the first storms observed by the NASA/JAXA GPM Core Observatory on March 17, 2014, in the eastern United States revealed a full range of precipitation, from rain to snow. 

Image courtesy NASA/JAXA.

The most accurate and comprehensive collection of rain, snowfall and other types of precipitation data ever assembled now is available to the public.

This new resource for climate studies, weather forecasting, and other applications is based on observations by the Global Precipitation Measurement (GPM) Core Observatory, a joint mission of NASA and the Japan Aerospace Exploration Agency (JAXA), with contributions from a constellation of international partner satellites.

The GPM Core Observatory, launched from Japan on Feb. 27, carries two advanced instruments to measure rainfall, snowfall, ice and other precipitation.

The advanced and precise data from the GPM Core Observatory are used to unify and standardize precipitation observations from other constellation satellites to produce the GPM mission data.

These data are freely available through NASA's Precipitation Processing System at Goddard Space Flight Center in Greenbelt, Maryland.

"We are very pleased to make all these data available to scientists and other users within six months of launch," said Ramesh Kakar, GPM program scientist in the Earth Science Division at NASA Headquarters, Washington.

Instruments on the GPM Core Observatory and partner satellites measure energy naturally emitted by liquid and frozen precipitation. Scientists use computer programs to convert these data into estimates of rain and snowfall.

The individual instruments on the partner satellites collect similar data, but the absolute numbers for precipitation observed over the same location may not be exactly the same.

The GPM Core Observatory's data are used as a reference standard to smooth out the individual differences, like a principal violinist tuning the individual instruments in an orchestra.

The result is data that are consistent with each other and can be meaningfully compared. With the higher sensitivity to different types of precipitation made possible by the GPM Core Observatory's Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR), scientists can for the first time accurately measure the full range of precipitation from heavy rain to light rain and snow.

The instruments are designed not only to detect rain and snow in the clouds, but to measure the size and distribution of the rain particles and snowflakes.

This information gives scientists a better estimate of water content and a new perspective on winter storms, especially near the poles where the majority of precipitation is snowfall.

"With this GPM mission data, we can now see snow in a way we could not before," said Gail Skofronick-Jackson, GPM project scientist at Goddard Space Flight Center.

"Cloud tops high in the atmosphere have ice in them. If the Earth's surface is above freezing, it melts into rain as it falls. But in some parts of the world, it's cold enough that the ice and snow falls all the way to the ground."