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| Titel |
Boundary conditions of an active West Antarctic subglacial lake: implications for storage of water beneath the ice sheet |
| VerfasserIn |
M. J. Siegert, N. Ross, H. Corr, B. Smith, T. Jordan, R. G. Bingham, F. Ferraccioli, D. M. Rippin, A. Le Brocq |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 1 ; Nr. 8, no. 1 (2014-01-03), S.15-24 |
| Datensatznummer |
250116003
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| Publikation (Nr.) |
 copernicus.org/tc-8-15-2014.pdf |
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| Zusammenfassung |
| Repeat-pass ICESat altimetry has revealed 124 discrete surface height
changes across the Antarctic Ice Sheet, interpreted to be caused by
subglacial lake discharges (surface lowering) and inputs (surface uplift).
Few of these active lakes have been confirmed by radio-echo sounding (RES)
despite several attempts (notable exceptions are Lake Whillans and three in
the Adventure Subglacial Trench). Here we present targeted RES and radar
altimeter data from an "active lake" location within the upstream Institute
Ice Stream, into which at least 0.12 km3 of water was previously
calculated to have flowed between October 2003 and February 2008. We use a
series of transects to establish an accurate depiction of the influences of
bed topography and ice surface elevation on water storage potential. The
location of surface height change is downstream of a subglacial hill on the
flank of a distinct topographic hollow, where RES reveals no obvious
evidence for deep (> 10 m) water. The regional hydropotential
reveals a sink coincident with the surface change, however. Governed by the
location of the hydrological sink, basal water will likely "drape" over
topography in a manner dissimilar to subglacial lakes where flat strong
specular RES reflections are measured. The inability of RES to detect the
active lake means that more of the Antarctic ice sheet bed may contain
stored water than is currently appreciated. Variation in ice surface
elevation data sets leads to significant alteration in calculations of the
local flow of basal water indicating the value of, and need for, high-resolution altimetry data in both space and time to establish and
characterise subglacial hydrological processes. |
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