HR: 0800h
AN: G31C-0803    [Abstracts]
TI: Climate-Driven Deformation of the Solid Earth from GRACE and GPS
AU: * Davis, J L
EM: jdavis@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 United States
AU: Elosegui, P
EM: pelosegui@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 United States
AU: Elosegui, P
EM: pelosegui@cfa.harvard.edu
AF: Institut Estudis Espacials Catalunya/CSIC, E-Nexus Gran Capita 2, Barcelona, 08034 Spain
AU: Mitrovica, J X
EM: jxm@terra.physics.utoronto.ca
AF: University of Toronto Ontario, Department of Physics 60 St. George St., Toronto, M5S 1A7 Canada
AU: Tamisiea, M E
EM: mtamisiea@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 United States
AB: Analysis of the global gravity field measured with the GRACE tandem satellites from the period 2002.3--2004.3 indicates large seasonal variations of gravity which are assumed to be related to climate-driven fluxes of surface water. A seasonal redistribution of surface mass should deform the Earth, and our calculations based on the GRACE data suggest radial (i.e., vertical) deformations with an amplitude of $\sim$13~mm in the region of greatest flux, the Amazon River Basin. To test the GRACE gravity-hydrology connection, we analyzed data for the same time period acquired by continuously operating GPS receivers located in this region. After adjusting for the degree-one (i.e., center of mass) difference between the geometric (GPS) and geodynamic (GRACE) reference frames, we find that annual amplitudes of radial deformation measured with GPS correlate significantly with predictions calculated from GRACE gravity variations. These results experimentally confirm the variations in surface water sensed by GRACE, which have been shown to be significantly larger than those predicted by hydrology models. These results also demonstrate that GRACE can be an important tool for monitoring deformation of the Earth, and suggests that comparison of GRACE and GPS data may be a useful approach for estimation of geocenter variations.
DE: 1833 Hydroclimatology
DE: 1214 Geopotential theory and determination
DE: 1229 Reference systems
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting