HR: 09:30h
AN: G31A-07    [PDF]
TI: Temporal Variations in the Earth's Gravitational Field: Modeling Results from a New Generation of GIA Models
AU: * Latychev, K
EM: latychev@physics.utoronto.ca
AF: University of Toronto, Dept. of Physics, 60 St. George Street, Toronto, ONT M5S 1A7 Canada
AU: Tamisiea, M
AF: University of Colorado, 440 UCB, Boulder, CO 80309 United States
AU: Mitrovica, J X
AF: University of Toronto, Dept. of Physics, 60 St. George Street, Toronto, ONT M5S 1A7 Canada
AU: Tromp, J
AF: California Institute of Technology, Seismological Laboratory, 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: Predictions of ongoing glacial isostatic adjustment (GIA) have played a central role in the interpretation of temporal variations in the Earth's gravitational field. Analyses of the spherical harmonic (zonal and nonzonal Stokes) coefficients of the secular change have, for example, followed two rather distinct philosophies: First, if all other contributions to satellite-derived observations are assumed to be known, then GIA predictions can be used to constrain Earth rheology or Late Pleistocene ice histories; Alternatively, observations may be corrected for the GIA signal and the residual signal used in some other geophysical analysis (e.g., constraining mass variations associated with ongoing hydrological, oceanographic and crysospheric processes). Previous predictions of the GIA signal have been based on simple, spherically symmetric (i.e., radially stratified) Earth models. With the initiation of a new set of gravity missions, the accuracy of the constraints on the Stokes coeficients will be significantly improved, and GIA models must evolve to incorporate the full complexity of the Earth system. In this talk, we present predictions of temporal gravity variations derived from a new generation of finite element models of the GIA process. Our models incorporate 3-D variations in mantle viscosity inferred (indirectly) from recent global seismic tomographic models as well as realistic lithospheric structures (including plate boundaries and regional thickness variations). We demonstrate the extent to which previous GIA predictions adopted in analyses extending over two decades have been biased by the assumption of spherical symmetry in mantle structure.
DE: 1234 Regional and global gravity anomalies and Earth structure
DE: 1236 Rheology of the lithosphere and mantle (8160)
DE: 3210 Modeling
DE: 3230 Numerical solutions
DE: 8120 Dynamics of lithosphere and mantle--general
SC: Geodesy [G]
MN: 2003 Fall Meeting