2008 Fall Meeting          
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Cite abstracts as Author(s) (2008), Title, Eos Trans. AGU,
(53), Fall Meet. Suppl., Abstract xxxxx-xx
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HR: 13:55h
TI: Measuring Surface Deformations Induced by Present-Day Ice Melting in Svalbard
AU: * Kierulf, H
EM: halfdan.kierulf@statkart.no
AF: Norwegian Mapping and Cadastre Authority, Kartverks vn 15., Honefoss, N-1362, Norway
AU: Plag, H
EM: hpplag@unv.edu
AF: University of Nevada, Mail Stop 178, Reno, 89557-0178, United States
AU: Kohler, J
EM: jack.kohler@npolar.no
AF: Norwegian Polar Institute, Polarmilj�senteret, Tromso, N-9296, Norway
AB: The vertical movement of the Earth's surface is the result of a number of internal processes in the solid Earth, tidal forces, and mass redistribution in the atmosphere, oceans, terrestrial hydrosphere, and cryosphere. Close to ice sheets and glaciers, the changes in the ice loads can induce large vertical motions at intra-seasonal to secular time scales. The GPS and VLBI antennas in Ny-AAlesund, Svalbard, which started observations in 1991 and 1994, respectively, observe vertical uplift rates on the order of 7 mm/yr and even higher for some geodetic solutions, which are considerably larger than those predicted by post-glacial rebound models (order 2 mm/yr). Despite the differences in secular uplift determined for the different sites and solutions, the inter- annual signal appears to be rather consistent across the different solutions. The time series exhibit a significant nonlinear behavior, with increased uplift rates starting some time in 2000. A local GPS campaign network, which has been reoccupied annually since 1998, reveals a tilting away from the neighboring ice sheet. The Svalbard ice sheets exhibit large melting during the last century and increased melting since about 2000. We compare the observed vertical motion to the motion predicted by loading models using a detailed ice model with annual time resolution as forcing. The model predictions correlate well with the observations both with respect to the inter-annual variations and the spatial pattern of long-term trends. The regression coefficients for predicted and observed inter-annual variations in height is 1.03±0.36, while the regression coefficient for the predicted and observed spatial pattern turns out to be 1.12±0.38. Estimates of the predicted secular trend in height due to post-glacial rebound and present-day melting are on the order of 5.5 mm/yr and thus smaller than the observed secular trend in height. This difference between predicted and observed secular trends may be due to reference frame effects or model biases.
DE: 1209 Tectonic deformation (6924)
DE: 1218 Mass balance (0762, 1223, 1631, 1836, 1843, 3010, 3322, 4532)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1295 Integrations of techniques
SC: Geodesy [G]
MN: 2008 Fall Meeting

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