Basal melting at the Ekstrom ice shelf, Antarctica, estimate

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TitleBasal melting at the Ekstrom ice shelf, Antarctica, estimated from mass flux divergenceAbstractWe characterize the basal mass balance of the Ekstrom Ice Shelf, Dronning Maud Land, Antarctica, using interferometrically derived surface velocities and ice thickness measurements from radio-echo sounding (RES). The surface velocities are based on data from European Remote-sensing Satellites-1 and -2 (ERS-1/2) during 1994-97. The ice thickness grid consists of 136 RES profiles acquired between 1996 and 2006. Mass fluxes are calculated along selected RES profiles where possible, to reduce uncertainties from ice thickness interpolation. Elsewhere large-scale mass fluxes are calculated using interpolated ice thickness data. Themass flux into the Ekstrom Ice Shelf from the main grounded drainage basins is estimated to be 3.19+-0.4Gt a-1. The mass flux near the ice shelf front is 2.67+-0.3Gt a-1. Assuming steady state, and based on the equation of continuity, we interpret the residual mass flux as a combined effect of snow accumulation and subglacial melting/refreezing. Using net snow accumulation rates from previous studies, we link the mass flux divergence in irregular-shaped polygons to processes beneath the ice shelf. The highest subglacial melt rates of Â Âº1.1ma-1 are found near the grounding zone of two main inflow glaciers, and around the German station Neumayer III. The detection of unlikely refreezing in a small area Â 15 km west of Neumayer III is attributed to both dataset inaccuracies and a (possibly past) violation of the steady-state assumption. In general, the method and input data allow mapping of the spatial distribution of basal melting and the results are in good agreement with several previous studies. Copyright 2012 Publishing Technology.AcknowledgementsWe thank D. Jansen for providing background literature, S. Ligtenberg, M. Helsen and M. van den Broeke for information about depth and density of the firn layer and J. Griggs and J. Bamber for the ice-shelf thickness from satellite radar altimetry. We also thank the Scientific Editor F. Straneo, O. Marsh and two anonymous reviewers for improving the manuscript. Preparation of this work was supported by a scholarship of the Evangelisches Studienwerk e.V. Villigst to R.D., and during an internship at Gateway Antarctica. We appreciate helpful discussions with O. Eisen. ERS data were made available through European Space Agency Project AO3.108.

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1st AuthorNeckel, N.AuthorNeckel, N.Drews, R.Rack, W.Steinhage, D.Year2012JournalAnnals of GlaciologyVolume53Number60Pages294-302DOI10.3189/2012AoG60A167URLhttps://www.scopus.com/inward/recor.....26e34a92e255b54b6c54d71ecKeywordsbasal flowbasal iceecho soundingERS-1ERS-2freeze-thaw cycleglacier dynamicsglacier mass balanceice thicknesssatellite data, AntarcticaEast AntarcticaEkstrom Ice Shelf, rank1

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TypeArticleCitationNeckel, N., Drews, R., Rack, W. and Steinhage, D. (2012) Basal melting at the Ekstrom ice shelf, Antarctica, estimated from mass flux divergence. Annals of Glaciology, 53(60):294-302 doi:10.3189/2012AoG60A167 IdentifierNeckel2012Relevancerank1