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More Accurate Measurement Of Earth's Water Found

Posted on: Friday, 8 October 2004, 06:00 CDT

Engineers at the University of Texas (UT) at Austin have developed the capability for measuring large-scale changes in the Earth's water availability. The development, according to university engineers, will make climate change studies much more accurate.

The engineers on the project used measurements of small changes in the Earth's gravitational field to provide the clearest picture yet of water's movement, above and below the Earth's surface.

The sub-surface measurements resulted from the National Aeronautics and Space Administration (NASA)/ German Aerospace Agency mission called the Gravity Recovery and Climate Experiment (GRACE). GRACE'S twin satellites have been orbiting the Earth for two years, producing monthly gravity maps up to 1,000 times more accurate than current maps. Because water variations introduce a change in mass, a gravity signal can be associated with this change. The engineers plan to use this signal to map more precise underground water sites, pressure variations at ocean floor depths and mean sea-level variations.

The GRACE satellites were launched in March 2002 as a joint project between NASA and the German Aerospace Center, GeoForschungsZentrum Potsdam. Achieving GRACE'S paradigm-shifting measurements required unique, cutting-edge engineering. The extreme sensitivity of the GRACE measurement is achieved through the use of two identical satellites flying in tandem in the same orbit plane.

According to NASA, the distance changes are measured with a precision equal to one-tenth the size of a human hair. Ultra- precise measurements are collected over the entirety of Earth's surface once each month in order to obtain the gravity signal.

Copyright Compass Publications, Inc. Sep 2004

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