HR: 08:45h
AN: G21A-04 INVITED     [PDF]
TI: Comparison of Geometric and Gravimetric Estimates of Surface Mass Transfer: Constraints on Geocenter Motion and Low-degree Love Numbers
AU: * Clarke, P J
EM: Peter.Clarke@newcastle.ac.uk
AF: School of Civil Engineering and Geosciences, Newcastle University, Newcastle, NE1 7RU United Kingdom
AU: * Clarke, P J
EM: Peter.Clarke@newcastle.ac.uk
AF: Colorado Center for Astrodynamics Research, University of Colorado, Boulder, CO 80309-0431 United States
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: School of Civil Engineering and Geosciences, Newcastle University, Newcastle, NE1 7RU United Kingdom
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: Nevada Bureau of Mines and Geology / Seismological Laboratory, University of Nevada, Reno, NV 89557-0088 United States
AU: Lavallee, D A
EM: lavallee@unr.edu
AF: Nevada Bureau of Mines and Geology / Seismological Laboratory, University of Nevada, Reno, NV 89557-0088 United States
AU: Pavlis, E C
EM: epavlis@JCET.umbc.edu
AF: Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD 21250 United States
AB: Mass redistribution on the surface of the Earth causes deformation of the solid Earth and translation of the solid Earth with respect to the whole Earth-ocean-atmosphere system (``geocenter motion''). These phenomena can be observed by tracking Earth-orbiting satellites from terrestrial observatories. For SLR tracking (generally of geodetic, LAGEOS-type satellites), non-gravitational forces are well modelled and so the orbit parameters and geocenter translation can be recovered quite precisely, despite the relative sparseness of the satellite constellation and tracking network. Conversely, in GPS tracking the forces acting on the satellites are less well modelled, and so direct estimates of geocenter translation are less precise. However, the greater density of the GPS constellation and tracking network allows the degree-1 deformation of the solid Earth to be estimated. Because the deformation and geocenter motion arise from the same surface mass distribution, comparison of the two constrains the ratio of Love numbers $h'_1/(1+k'_1)$ applicable at periods from weeks to years. At degrees 2 and higher, multi-satellite SLR analyses have sufficient strength to solve for the time-varying zonal gravitational potential field. As at degree 1, this potential field must arise from the same surface mass redistribution that causes deformation of the solid Earth. We compare GPS estimates of higher-degree zonal deformation with recent SLR estimates of zonal gravitational potential change (Cox and Chao, Science 297, 2002). This method is in principle capable of constraining the degree-$n$ Love number ratio $h'_n/(1+k'_n)$ applicable at fortnightly to interannual periods.
DE: 1213 Earth's interior--dynamics (8115, 8120)
DE: 1214 Geopotential theory and determination
DE: 1243 Space geodetic surveys
DE: 1247 Terrestrial reference systems
DE: 1655 Water cycles (1836)
SC: Geodesy [G]
MN: 2003 Fall Meeting