HR: 11:50h
AN: G31C-07    [PDF]
TI: Recent Small Glacier Mass Balance Signatures in Time-Variable Gravity
AU: * Tamisiea, M E
EM: tamisiea@colorado.edu
AF: University of Colorado, CB 440, Boulder, CO 80309 United States
AU: Mitrovica, J X
EM: jxm@physics.utoronto.ca
AF: University of Toronto, Department of Physics, 60 St. George St., Toronto, ON M5S 1A7 Canada
AU: Davis, J L
EM: jdavis@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 United States
AB: The global reservoir of small (or mountain) glaciers may be experiencing an accelerated phase of net melting. Estimates of the recent mass balance of large systems of such glaciers using point measurements of accumulation and discharge rates or changes in ice sheet height along profiles obtained from altimetry are subject to biases associated with incomplete sampling. Integrated measurements, such as changes in sea level and the geoid (or sea surface) are more robust in this specific sense. However, these variations may be contaminated by signals from past (i.e., Pleistocene to Late Holocene) glacial fluctuations. As an example, in regions with low asthenospheric viscosity, such as Alaska and Patagonia, predictions of radial crustal motion (and thus sea level) are known to be highly sensitive to the local glacier history over the last few thousand years [e.g., Ivins and James, 1999, Larsen et al., 2003; Tamisiea et al., 2003]. In contrast, the predicted geoid (sea surface) variation in the same regions is insensitive to this aspect of the loading history [Tamisiea et al., 2003]. In this talk we extend this work to consider predictions of present-day geoid patterns arising from past glacial fluctuations of various time scales. We demonstrate that measurements of geoid variations in the vicinity of small glacier systems provide a remarkably robust (i.e., uncontaminated) measure of the ongoing mass balance of these systems. We conclude that such measurements should be a key target of existing and future satellite gravity missions.
DE: 1236 Rheology of the lithosphere and mantle (8160)
DE: 1645 Solid Earth
DE: 4556 Sea level variations
SC: Geodesy [G]
MN: 2003 Fall Meeting