GRACE also detects changes in the gravity field due to geophysical processes. GeophysicsĬhange in mass of the Greenland and Antarctic ice sheets as measured by GRACE Ī University of California, Irvine-led study published in Water Resources Research on 16 June 2015 used GRACE data between 20 to conclude that 21 of the world's 37 largest aquifers "have exceeded sustainability tipping points and are being depleted" and thirteen of them are "considered significantly distressed." The most over-stressed is the Arabian Aquifer System, upon which more than 60 million people depend for water. The annual hydrology of the Amazon basin provides an especially strong signal when viewed by GRACE. GRACE data have also provided insights into regional hydrology inaccessible to other forms of remote sensing: for example, groundwater depletion in India and California. These equate to a total of 0.9 mm/yr of sea level rise. Greenland has been found to lose 280±58 Gt of ice per year between 20, while Antarctica has lost 67±44 Gt per year in the same period. GRACE data have provided a record of mass loss within the ice sheets of Greenland and Antarctica. GRACE enables separation of those two effects to better measure ocean currents and their effect on climate. The hills and valleys in the ocean's surface (ocean surface topography) are due to currents and variations in Earth's gravity field. High-resolution static gravity fields estimated from GRACE data have helped improve the understanding of global ocean circulation. GRACE data are critical in helping to determine the cause of sea level rise, whether it is the result of mass being added to the ocean, from melting glaciers, for example, or from thermal expansion of warming water or changes in salinity. ![]() Scientists have also detailed improved methods for using GRACE data to describe Earth's gravity field. The limited resolution of GRACE is acceptable in this research because large ocean currents can also be estimated and verified by an ocean buoy network. For example, measuring ocean pressure gradients allows scientists to estimate monthly changes in deep ocean currents. Scientists use GRACE data to estimate ocean bottom pressure (the combined weight of the ocean waters and atmosphere), which is as important to oceanographers as atmospheric pressure is to meteorologists. GRACE chiefly detected changes in the distribution of water across the planet. įrom the thinning of ice sheets to the flow of water through aquifers and the slow currents of magma inside Earth, mass measurements provided by GRACE help scientists better understand these important natural processes. The monthly gravity anomalies maps generated by GRACE are up to 1,000 times more accurate than previous maps, substantially improving the accuracy of many techniques used by oceanographers, hydrologists, glaciologists, geologists and other scientists to study phenomena that influence climate. Variations in ocean bottom pressure measured by GRACE Its successor, GRACE-FO, was successfully launched on. GRACE far exceeded its 5-year design lifespan, operating for 15 years until the decommissioning of GRACE-2 on 27 October 2017. This system was able to gather global coverage every 30 days. During normal operations, the satellites were separated by 220 km along their orbit track. The spacecraft were launched to an initial altitude of approximately 500 km at a near-polar inclination of 89°. The two GRACE satellites (GRACE-1 and GRACE-2) were launched from Plesetsk Cosmodrome, Russia, on a Rockot (SS-19 + Breeze upper stage) launch vehicle on 17 March 2002. The principal investigator is Byron Tapley of the University of Texas Center for Space Research, and the co-principal investigator is Christoph Reigber of the GeoForschungsZentrum (GFZ) Potsdam. The Jet Propulsion Laboratory was responsible for the overall mission management under the NASA ESSP (Earth System Science Pathfinder) program. GRACE was a collaborative endeavor involving the Center for Space Research at the University of Texas at Austin, NASA's Jet Propulsion Laboratory, the German Aerospace Center and Germany's National Research Center for Geosciences, Potsdam. Data from the GRACE satellites is an important tool for studying Earth's ocean, geology, and climate. By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time. ![]() ![]() Twin satellites took detailed measurements of Earth's gravity field anomalies from its launch in March 2002 to the end of its science mission in October 2017. File:15 Years of Freshwater Trends Seen by GRACE.webm The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center.
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