NASA Precipitation Processing System © nasa gov
Weather forecasts. 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.
In addition to NASA and JAXA, the GPM mission includes satellites from the U.S. National Oceanic and Atmospheric Administration, U.S. Department of Defense’s Defense Meteorological Satellite Program, European Organisation for the Exploitation of Meteorological Satellites, Indian Space Research Organisation, and France’s Centre National d’Études Spatiales.
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 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 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.”
One of the first storms observed by the GPM Core Observatory on March 17 in the eastern United States showed that full range of precipitation. Heavy rains fell over the North and South Carolina coasts. As the storm moved northward, West Virginia, Virginia, Maryland and Washington were covered with snow. The GMI observed an 547 mile- (880 kilometer) wide track of precipitation on the surface, while the DPR imaged every 820 feet (250 meters) vertically to get the three-dimensional structure of the rain and snowfall layer by layer inside the clouds.
NASA Precipitation Processing System © nasa gov |
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