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Ian M. Howat et al.: Rates of southeast Greenland ice volume loss from combined ICESat and ASTER observations

Geophysical Research Letters, Vol. 35, L17505; doi:10.1029/2008GL034496, 2008

Rates of southeast Greenland ice volume loss from combined ICESat and ASTER observations

Ian M. Howat (School of Earth Sciences and Byrd Polar Research Center, Ohio State University, Columbus, OH, U.S.A.), Ben E. Smith (Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, U.S.A.), Ian Joughin (Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, U.S.A.), Ted A. Scambos (National Snow and Ice Data Center, University of Colorado, Boulder, CO, U.S.A.)

Abstract

Repeat satellite laser altimetry is critical for observing the rapidly changing mass balance of the Greenland Ice Sheet. However, sparse sampling and high surface slopes over rapidly thinning, coastal outlet glaciers may result in underestimation of mass loss. Here we supplement ICESat-derived surface elevation changes with differenced ASTER digital elevation models of outlet glaciers in southeastern Greenland, the region with the largest concentrated change in outlet glacier mass loss. We estimate a 2002–2005 regional volume-loss rate of 108 km3/yr. Our results are consistent with drainage-scale GRACE and mass-budget estimates when differences in observation periods are taken into account. The two largest glaciers, Kangerdlugssuaq and Helheim, account for only 28% of the mass loss, illustrating the combined importance of smaller glaciers and the need for complete observational coverage. Additionally, we find that rapid, concentrated thinning within the outlets represents a small contribution to the total volume change compared to dispersed inland thinning.

(Received 28 April 2008, accepted 29 July 2008, published 9 September 2008.)

Key words: Greenland, ice sheet, mass balance

Index Terms: 0762 Cryosphere: Mass balance (1218, 1223); 0726 Cryosphere: Ice sheets; 0758 Cryosphere: Remote sensing; 0776 Cryosphere: Glaciology (1621, 1827, 1863); 0720 Cryosphere: Glaciers.

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Citation: Howat, I. M., B. E. Smith, I. Joughin, and T. A. Scambos (2008), Rates of southeast Greenland ice volume loss from combined ICESat and ASTER observations, Geophys. Res. Lett., 35, L17505, doi:10.1029/2008GL034496.