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| Titel |
Evidence of meltwater retention within the Greenland ice sheet |
| VerfasserIn |
A. K. Rennermalm, L. C. Smith, V. W. Chu, J. E. Box, R. R. Forster, M. R. Broeke, D. As, S. E. Moustafa |
| 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 ; 7, no. 5 ; Nr. 7, no. 5 (2013-09-23), S.1433-1445 |
| Datensatznummer |
250085158
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| Publikation (Nr.) |
 copernicus.org/tc-7-1433-2013.pdf |
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| Zusammenfassung |
| Greenland ice sheet mass losses have increased in recent decades with more
than half of these attributed to surface meltwater runoff. However, the
magnitudes of englacial storage, firn retention, internal refreezing and
other hydrologic processes that delay or reduce true water export to the
global ocean remain less understood, partly due to a scarcity of in situ
measurements. Here, ice sheet surface meltwater runoff and proglacial river
discharge between 2008 and 2010 near Kangerlussuaq, southwestern Greenland
were used to establish sub- and englacial meltwater storage for a small ice
sheet watershed (36–64 km2). This watershed lacks significant
potential meltwater storage in firn, surface lakes on the ice sheet and in
the proglacial area, and receives limited proglacial precipitation. Thus, ice
sheet surface runoff not accounted for by river discharge can reasonably be
attributed to retention in sub- and englacial storage. Evidence for meltwater
storage within the ice sheet includes (1) characteristic dampened daily river
discharge amplitudes relative to ice sheet runoff; (2) three cold-season
river discharge anomalies at times with limited ice sheet surface melt,
demonstrating that meltwater may be retained up to 1–6 months; (3) annual
ice sheet watershed runoff is not balanced by river discharge, and while near
water budget closure is possible as much as 54% of melting season ice
sheet runoff may not escape to downstream rivers; (4) even the large
meltwater retention estimate (54%) is equivalent to less than 1% of the
ice sheet volume, which suggests that storage in en- and subglacial cavities
and till is plausible. While this study is the first to provide evidence for
meltwater retention and delayed release within the Greenland ice sheet, more
information is needed to establish how widespread this is along the Greenland
ice sheet perimeter. |
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