HR: 08:00h
AN: G31A-01 INVITED     [Abstracts]
TI: Geocenter Motions From Satellite Geodesy; A Unified Observation Model
AU: * Lavallée, D A
EM: d.a.lavallee@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: van Dam, T
EM: tvd@ecgs.lu
AF: European Center for Geodynamics and Seismology, 19 Rue Josy Welter, Walferdange, L-7256 Luxembourg
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: University of Nevada, Reno, Mackay School of Earth Science and Engineering Mail Stop 178, Reno, NV 89557 United States
AU: Clarke, P J
EM: peter.clarke@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Moore, P
EM: Philip.Moore@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Zhang, Q
EM: Qiang.Zhang@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Newcastle upon Tyne, NE1 7RU United Kingdom
AB: Changes in the displacement vector between the Center of Mass (CM) of the Earth system and the Center of the Earth's geometrical Figure (CF) is commonly called geocenter motion and is observable using geodetic techniques. Estimates of this geocenter motion have been at various levels of agreement both between and within different geodetic techniques. Cross-technique differences can be partly explained by a broad spectrum of technique specific errors and different tracking networks. Geocenter motions on the intra-annual scale are caused by global scale surface mass re-distribution which causes elastic deformation of the solid Earth and displaces the center of the geodetic tracking network (and hence CF) from CM. Given this underlying physical process we can unify expected changes in both deformation and gravity through an elastic Earth model and build a much stronger framework for estimating geocenter motions than via deformational or empirical approaches alone. Using such a unified approach allows a contribution to be made by techniques that are not directly sensitive to station displacements (such as satellite gravity measurements) or alternatively allows techniques that are not sensitive to gravitational aspects of frame definition (i.e. the origin) to contribute via observations of relative site motion. This is particularly pertinent for GPS which can exploit good spatial coverage and provide low inter-site estimation precision but has a less precise determination of the center of mass and hence the origin of the frame. We demonstrate how a unified model can be applied to geocenter motion estimation using GPS solutions from the IGS analysis centers. Through a combination of error propagation and simulation we show how a model that unifies both the shift and inter-site motion is conceptually stronger for GPS than one based on either alone, or a "common-mode" filter approach. We further investigate the contribution to be made by adding observations of the temporal gravity field from SLR such that different techniques have complementary input.
DE: 1200 GEODESY AND GRAVITY
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 1229 Reference systems
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
SC: Geodesy [G]
MN: Fall Meeting 2005