HR: 10:50h
AN: G42A-03    [Abstracts]
TI: The GGM03 Mean Earth Gravity Model from GRACE
AU: Tapley, B
EM: tapley@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AU: * Ries, J
EM: ries@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AU: Bettadpur, S
EM: srinivas@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AU: Chambers, D
EM: chambers@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AU: Cheng, M
EM: cheng@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AU: Condi, F
EM: condi@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AU: Poole, S
EM: poole@csr.utexas.edu
AF: Center for Space Research, R1000 The University of Texas at Austin, Austin, TX 78712, United States
AB: A new generation Earth gravity field model, called GGM03S, is derived using four years of data spanning January 2003 to December 2006 from the Gravity Recovery and Climate Experiment. Relative to the preceding generation, GGM02, there have been improvements to the data products, the gravity estimation methods and the background models. Based on the calibrated covariance, GGM03S represents a factor of two improvement over the previous GGM02 model. The satellite only model determined from the GRACE data is combined with surface measurements to obtain an improved combined model, referred to as GGM 03C, that is complete to degree and order 360. The optimal combination of the very precise gravity information from GRACE with terrestrial and marine gravity information is a challenging task. Avoiding degradation of the portion of the gravity solution from GRACE is one difficulty, as is the specific solution method to achieve a degree and order 360 model. Traditional techniques require the use of block diagonal or quadrature-like methods. Using a new 'out-of-core' algorithm, a rigorous estimate of a full 360x360 field (with full covariance) has been obtained. By ingesting the terrestrial and marine gravity information directly, assumptions about density required for reducing data to a single surface are not required, nor are there any restrictions on data type, distribution, spacing or weighting. This presentation will briefly describe the two solutions and present preliminary evaluations of the improvement in the model accuracy
DE: 1214 Geopotential theory and determination (0903)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
SC: Geodesy [G]
MN: 2007 Fall Meeting