HR: 11:35h
AN: G31C-06    [PDF]
TI: An Investigation of Recent Gravity Variations Using Geophysical "Fingerprints"
AU: * Nerem, R S
EM: nerem@colorado.edu
AF: Colorado Center for Astrodynamics Research, University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AU: Cox, C M
EM: ccox@stokes.gsfc.nasa.gov
AF: Raytheon ITSS, NASA/GSFC, Code 926, Greenbelt, MD 20771 United States
AU: Leuliette, E W
EM: Eric.Leuliette@colorado.edu
AF: Colorado Center for Astrodynamics Research, University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AU: Thompson, B F
EM: Blair.Thompson@colorado.edu
AF: Colorado Center for Astrodynamics Research, University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AB: Recently, Satellite Laser Ranging (SLR) data have been used to detect a large change in the Earth's oblateness during 1998-2002 [Cox and Chao, 2002]. The leading candidates for the cause of this change are mass redistribution in the oceans and the melting of mountain glaciers [Dickey et al., 2002]. Most studies of this phenomena have employed estimates of the low-degree spherical harmonic coefficients in comparisons of the observations and the models. Here, we present preliminary results using the same SLR observations to estimate the amplitude of geophysical "fingerprints" describing mass redistribution in different components of the Earth system (Antarctica, Greenland, post-glacial rebound, ocean-continent mass exchange, mountain glaciers, etc.). We take spherical harmonic expansions of these fingerprints, and use them to linearly transform the SLR spherical harmonic solutions into a set of new parameters that describes the estimated amplitude of each of the fingerprints. This is done on a monthly basis from 1980-2002 (bimonthly before 1992) so that the time variation of the amplitude coefficients may be studied. We will present an interpretation of these results in the context of investigation the anomalous gravity variations during 1998-2002. While this technique is particularly useful for a spatially sparse dataset such as is provided by SLR, we will also discuss the benefit of analyzing data from the CHAMP and GRACE missions using this same technique.
DE: 1214 Geopotential theory and determination
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: 2003 Fall Meeting