HR: 10:35h
AN: G41C-02 INVITED     [PDF]
TI: Applying Surface Load Models to GPS Coordinates: the Effects of Mass Conservation and Gravitational Consistency
AU: * Clarke, P J
EM: Peter.Clarke@newcastle.ac.uk
AF: School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, 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, University of Newcastle upon Tyne, Newcastle, NE1 7RU United Kingdom
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: Nevada Bureau of Mines and Geology and 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 and Seismological Laboratory, University of Nevada, Reno, NV 89557-0088 United States
AU: van Dam, T
EM: tvd@ecgs.lu
AF: European Center for Geodynamics and Seismology, Rue Josy Welter, 19, Walferdange, L-7256 Luxembourg
AU: Wahr, J M
EM: wahr@lemond.colorado.edu
AF: Department of Physics and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309-0390 United States
AB: Increasingly, models of surface mass loads (atmosphere, ground water, continental snow/ice, and circulation-induced ocean bottom pressure) are used either to correct geodetic time series by removing seasonal and other ``noise'', or for comparison with geodetic parameters related to surface mass transfer. However, models of surface loading obtained by simply combining the mass redistribution due to individual phenomena will not in general be self-consistent, in that (i) the implied global water budget will not be mass-conserving, and (ii) the modelled sea level will not be an equipotential surface of the Earth system's total gravity field. We force closure of the global water budget by allowing the ``passive'' ocean (unrelated to circulation effects) to change in mass. As has been previously recognised for the much larger sea-level changes that occur in glacial isostatic adjustment, this passive ocean response will not be a uniform change in non-steric ocean surface height, but must necessarily be variable so as to keep the ``passive'' ocean surface on an equipotential (at periods of more than a few days). We demonstrate the effect that this forcing of physical consistency has on seasonal loading models, and compare our results with recent observations from global GPS analyses.
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
DE: 1247 Terrestrial reference systems
DE: 1655 Water cycles (1836)
DE: 4227 Diurnal, seasonal, and annual cycles
DE: 4556 Sea level variations
SC: Geodesy [G]
MN: 2003 Fall Meeting