HR: 0800h
AN: C51A-0080    [Abstracts]
TI: Contemporary ice-mass changes and glacial-isostatic adjustment in the polar regions from GRACE
AU: Sasgen, I
EM: sasgen@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg A17, Potsdam, 14467, Germany
AU: Martinec, Z
EM: zdenek@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg A17, Potsdam, 14467, Germany
AU: * Fleming, K
EM: kevin@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg A17, Potsdam, 14467, Germany
AB: Mass changes in the polar regions are inferred by making use of about 4 years of Gravity Recovery and Climate Experiment (GRACE) gravity fields. The time series of each of the Stokes coefficients are decomposed into their linear, annual and semi-annual components, and we apply the Student's t-test to assess the statistical significance of the linear temporal trends in the Stokes potential coefficients. We solve the inverse-gravimetric problem by adjusting forward models describing the prominent geoid-height changes arising from ice-mass changes in Antarctica, Greenland, Alaska and Patagonia, and of the glacial-isostatic adjustment (GIA) due to the last glacial-interglacial transition. We show that, although all used data sets (GFZ, CSR; JPL and CNES) consistently reflect the prominent mass changes, differences in the mass-change estimates are considerably larger than the uncertainties estimated by the propagation of the GRACE errors. We then use the bootstrapping method based on the four releases and six time intervals, each with 3.5 years of data, to quantify the variability in the mean mass-change estimates. We find that for most regions the variability of the mass changes estimates lies below +/-50% demonstrating the reliability of results obtained using GRACE observations.
DE: 0726 Ice sheets
DE: 0758 Remote sensing
DE: 0776 Glaciology (1621, 1827, 1863)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
SC: Cryosphere [C]
MN: 2007 Fall Meeting