HR: 16:45h
AN: G24A-04    [Abstracts]
TI: Ocean mass redistribution and its impact on non-tidal terrestrial and space geodetic observations over land
AU: Gross, R S
EM: Richard.S.Gross@jpl.nasa.gov
AF: JPL/Caltech, 4800 Oak Grove Drive M/S 238-600, Pasadena, CA 91109-8099 United States
AU: * Ivins, E R
EM: eri@fryxell.jpl.nasa.gov
AF: JPL/Caltech, 4800 Oak Grove Drive M/S 238-600, Pasadena, CA 91109-8099 United States
AB: One of the more difficult problems with the determination of the geophysical origins for interannual and interdecadal trends in geoid, local gravity and displacement of the solid earth is the influence of loading from the non-tidal components of ocean mass redistribution. For example, isolating the postglacial rebound components of secular trends in geodetic data may require estimation of the longest period variability in non-tidal ocean mass loading. In Antarctica, where terrestrial data sets typically are non-continuous, consideration of non-tidal ocean effects may be critical. A number of questions in Antarctic geodesy are posed: How large are ocean loading effects due to the Antarctic Circumpolar Current (ACC)? Antarctic Circumpolar Wave (ACW) appears to have a transit time of about 8 years, therefore, how do inter- and/or intra-decadal ocean signals influence `on-land' residuals, and how might such signals mimic secular signals? What are the implications for employing GRACE, GOCE, IceSAT and bedrock GPS and/or gravity observations? We examine the time/space spectral character of non-tidal ocean loading using model results from both a 50-year-long simulation of the oceans' circulation and from a 12-year-long data assimilated ocean model run, both produced by the ECCO/JPL group. After correcting for artifical mass changes caused by the use of the Boussinesq approximation in both model runs, they predict similar large-scale mass redistributions during their common time span. Changes in the geoid to spherical harmonic degree and order 72 are computed from the modeled ocean bottom pressure changes. Deep within the Antarctic interior seasonal ocean geoid variability is at the 3 mm peak-to-peak level and vertical height variation are of order 5-8 mm. Similar amplitude long-wavelength perturbations transit the Eurasian continent, Africa, the Americas and Australia. The amplitude and spectral character of these geophysical signals are important considerations for any reanalysis of data from SLR, VLBI, GPS networks, and of high-quality gravimetric station data.
DE: 1211 Non-tectonic deformation
DE: 1222 Ocean monitoring with geodetic techniques (1225, 1641, 3010, 4532, 4556, 4560, 6959)
DE: 1243 Space geodetic surveys
DE: 1295 Integrations of techniques
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
SC: Geodesy [G]
MN: Fall Meeting 2005