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Validation of Gravity Models from CHAMP/GRACE Gravity Missions Using the GPS/leveling Data from the Continental US. Yan M. Wang and D.R. Roman National Geodetic Survey NOAA Potsdam, Germany, July 5-9, 2004. Overview.
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Validation of Gravity Models from CHAMP/GRACE Gravity Missions Using the GPS/leveling Data from the Continental US Yan M. Wang and D.R. Roman National Geodetic Survey NOAA Potsdam, Germany, July 5-9, 2004
Overview • Validate GGM01S/C & EIGEN_3P against 14460 GPS/leveling implied geoid undulations scattered over the U.S. and parts of Canada • Compare GGM01S/C & EIGEN_3P to geoid changes deduced from 10 years of TOPEX/Poseidon altimetry data over the Great Lakes
GPS/leveling Comparisons Comparison description: • Geoid is computed from coefficient models in full degree and order and to degree and order 90, then augmented with EGM96 to degree 360 • GPS/leveling data are converted from NAVD88 to ITRF96, then compared with models
Lake Geoid Comparisons Comparison description: • Lake surface is an equipotential surface • 10 years of TOPEX/Poseidon altimeter data provide accurate mean lake surface with 2-3 cm accuracy (Beckley, private communication) • Geoid changes are compared over two tracks (Lake Superior and Huron)
Conclusions • Cutoff degree and orders at 90 for all models and augmented by EGM96 to 360 improves the comparisons • GGM01S (n<=90)+EGM96 performs the best in GPS/leveling comparisons • GGM01C performs the best in lake surface comparisons • Recommendations: GGM01S (n<=90)+EGM96 is recommended
Web Information • Lake monitoring program supported by USDA: http://www.pecad.fas.usda.gov/cropexplorer/global_reservoir