Alan Buis 818-354-0474 Jet Propulsion Laboratory, Pasadena, Calif.
Erica Hupp/Dwayne Brown 202-358-1237/1726 NASA Headquarters,
News Release: 2006-146 Dec. 12, 2006
NASA Outlines Recent Changes in Earth's Freshwater Distribution
Recent space observations of freshwater storage by the Gravity Recovery and Climate Experiment (Grace) are providing a new picture of how Earth's most precious natural resource is distributed globally and how it is changing.
Researchers are using the mission's almost five-year data record to estimate seasonal water storage variations in more than 50 river basins that cover most of Earth's land area. The variations reflect changes in water stored in rivers, lakes and reservoirs; in floodplains as snow and ice; and underground in soils and aquifers.
"Grace is providing a first-ever look at the distribution of freshwater storage on the continents," said Dr. Jay Famiglietti, professor of Earth System Science,
Several African basins, such as the
The twin Grace satellites monitor tiny month-to-month changes in Earth's gravity field that are primarily caused by the movement of water in Earth's land, ocean, ice and atmosphere reservoirs. Hydrologists are analyzing Grace data to identify possible trends in precipitation changes, groundwater depletion and snow and glacier melt rates, and to understand their underlying causes.
Dr. Matt Rodell, a hydrologist at NASA's
Dr. Michael Watkins, Grace project scientist at NASA's Jet Propulsion Laboratory,
The mission's abilities to detect water are particularly vital for the emerging field of groundwater remote sensing. "Remote sensing of groundwater has been a Holy Grail for hydrologists because it is stored beneath the surface and is not detected by most sensors," said Famiglietti. "Outside of the
Grace is also allowing scientists to estimate another key component of the water cycle for the first time: water discharged by freshwater streams from Earth's continents. Stream flow measurements are often not shared for economic, political or national defense reasons. Grace measurements of the total water discharged by continental streams are important for monitoring the availability of freshwater and understanding how surface water runoff from continents contributes to rises in global sea level.
Scientists from NASA and the
Grace is a partnership between NASA and the German Aerospace Center (DLR). The University of Texas Center for Space Research, Austin, has overall mission responsibility. JPL developed the two Grace satellites. DLR provided the launch, and the GeoForschungsZentrum Potsdam, Germany, operates the Grace mission.
For more information about Grace, see http://www.csr.utexas.edu/grace/ . For more on NASA water and energy cycle research, visit http://watercycle.gsfc.nasa.gov/index.php. Other media contacts: Margaret Baguio, University of Texas Center for Space Research, Austin, 512-471-6922; Jennifer Fitzenberger, University of California,
Additional information on NASA news from the American Geophysical Union conference is at http://www.nasa.gov/agu .
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