HR: 16:40h
AN: G23A-12    [Abstracts]
TI: Feasibility of Using GRACE Gravity Observations to Constrain the Annual Mass Variation of Glacier Complexes Near the Gulf of Alaska
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 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: Mountain glaciers make a significant contribution to the global hydrological cycle though they only constitute 3 to 4% of the Earth's glaciated land area. Unfortunately, determining the total annual and secular contribution from the large glacier complexes is difficult using standard glaciological and aerial altimetric methods. To obtain the annual mass balance, glaciological methods generally sample a small number of geographic sites and difference measurements taken at two times during the year. Aerial altimetry improves the geographic sampling but differences measurements taken once during the same period each year. We explore the use of the GRACE monthly fields in combination with other geodetic techniques (e.g., GPS) to examine the annual component and to better constrain the annual mass balance for the glacier complexes near the Gulf of Alaska. This data set allows for much better temporal sampling of the mass change and is an integrated measure of the mass balance across all of the glacier complexes in the region. We use a technique presented by Davis et al. [2004 Fall AGU, Session G12], which only uses spherical harmonic coefficients with a statistically significant annual component, as well as methods using Gaussian filters [e.g., Swenson and Wahr, 2002] to estimate the annual amplitude of the total mass variation over the region including most of the glaciers near the Gulf of Alaska. We present the observations as well as results from forward models processed in the same manner and discuss the ability of these approaches to obtain the annual mass variation of the glacier complexes.
DE: 4556 Sea level variations
DE: 1827 Glaciology (1863)
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting