HR: 1340h
AN: G33B-0043    [Abstracts]
TI: Use of Scaling to Identify Glacier Mass Flux in GRACE Data
AU: * Tamisiea, M E
EM: mtamisiea@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS 42, Cambridge, MA 02138 United States
AU: Leuliette, E W
EM: Eric.Leuliette@colorado.edu
AF: Colorado Center for Astrodynamics Research, University of Colorado, CB 431, Boulder, CO 80309-0431 United States
AU: Davis, J L
EM: jdavis@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS 42, Cambridge, MA 02138 United States
AU: Mitrovica, J X
EM: jxm@physics.utoronto.ca
AF: Department of Physics, University of Toronto, 60 St. George St., Toronto, ON M5S 1A7 Canada
AB: Many glacier complexes, such as those in Patagonia and S.E. Alaska, are experiencing rapid changes in volume. Unfortunately, detecting these mass variations with GRACE data is difficult due to the small spatial extent of the glacial complexes. Specifically, smoothing is applied to the GRACE data in order to reduce satellite errors that tend to increase with decreasing wavelengths, and thus spatial averages centered over glaciated regions will capture surrounding regions with smaller mass variations. The greater the smoothing, the smaller the estimated mass change. Conversely, as the applied smoothing is reduced, the inferred mass flux (and error in this inference) increases. We describe a technique whereby the trend between mass flux estimate and the smoothing length scale applied to the GRACE data can be extrapolated to the zero-smoothing case using scaling relationships derived from forward predictions. Applied to the Alaskan glacier complexes, this technique has been shown [Tamisiea et. al, GRL, submitted] to yield robust estimates of the annual amplitude and trend of the surface mass, with the latter suggesting a contribution to sea level rise of 0.31±0.09~mm/yr from 2002 to 2004. We describe this work, and also demonstrate the application of the scaling procedure to other areas, including the Patagonian glacier complexes. Finally, we also explore whether similar results may be obtained using standard techniques that simultaneously minimize the satellite and leakage errors [e.g., Swenson and Wahr, 2003], where the scaling might be dependent on the total error instead of the applied smoothing.
DE: 0720 Glaciers
DE: 0762 Mass balance (1218, 1223)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1641 Sea level change (1222, 1225, 4556)
SC: Geodesy [G]
MN: Fall Meeting 2005