Slow zoom out starting over the United States revealing the rest of the world.
GRACE (Gravity Recovery and Climate Experiment) maps variations in Earth's gravity field. GRACE consists of two identical spacecraft that fly about 220 kilometers (137 miles) apart in a polar orbit 500 kilometers (310 miles) above Earth. GRACE maps Earth's gravity field by making accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. It is providing scientists from all over the world with an efficient and cost-effective way to map Earth's gravity field with unprecedented accuracy. The results from this mission are yielding crucial information about the distribution and flow of mass within Earth and its surroundings.
The gravity variations studied by GRACE can be used to determine ground water storage on land masses. By comparing current data to an average over time, scientists can generate an anomaly map to see where ground water storage has been depleted or increased.
GRACE is a joint partnership between the National Aeronautics and Space Administration (NASA) in the United States and Deutsche Forschungsanstalt für Luft und Raumfahrt (DLR) in Germany. Project management and systems engineering activities are carried out by the Jet Propulsion Laboratory.
GRACE Terrestrial Water Storage Anomaly colorbar. Rust colored areas show areas where ground water has decreased, and areas in blue are where ground water levels have increased. Note the significant decreases in ground water storage across most of California and all the way up the North American coast into Alaska.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 22.214.171.124.0