HR: 14:50h
AN: G13A-06    [Abstracts]
TI: Long Wavelength Dynamics of an Ice Age Earth: Implications for GRACE
AU: * Mitrovica, J X
EM: jxm@physics.utoronto.ca
AF: Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Wahr, J
EM: wahr@lemond.colorado.edu
AF: Department of Physics, University of Colorado, Campus Box 390, Boulder, CO 30809 United States
AU: Matsuyama, I
EM: isamu@astro.utoronto.ca
AF: Department of Astronomy and Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 Canada
AU: Paulson, A
EM: archie.paulson@colorado.edu
AF: Department of Physics, University of Colorado, Campus Box 390, Boulder, CO 30809 United States
AU: Tamisiea, M
EM: mtamisiea@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS42, Cambridge, MA 02138 United States
AB: The remnant gravitational signature of the Earth's response to the Late Pleistocene glacial cycles, or glacial isostatic adjustment (GIA), is a primary target of the GRACE satellite gravity mission. At the longest wavelengths, numerical simulations of the secular variation in the geopotential due to GIA exhibit a pronounced (degree two, order one) anomaly associated with so-called `rotational feedback'. That is, a perturbation in the geopotential arising from GIA-induced deflections in the Earth's rotation vector. The amplitude of the feedback signal is a function of the adopted Earth model and it has been the source of ongoing debate within the GIA literature. We revisit this issue using a new treatment of the equations governing load-induced rotation perturbations on spherically symmetric, viscoelastic Earth models. We demonstrate that previous estimates of the rotational feedback signal in present day rates of change of the geopotential (and also crustal velocities) have been significantly overestimated by the traditional rotation theory. This result has important implications for the analysis of secular trends constrained by the GRACE satellite mission.
DE: 1213 Earth's interior--dynamics (8115, 8120)
DE: 1227 Planetary geodesy and gravity (5420, 5714, 6019)
DE: 1239 Rotational variations
SC: Geodesy [G]
MN: 2005 Joint Assembly