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| Titel |
Modelling the transfer of supraglacial meltwater to the bed of Leverett Glacier, Southwest Greenland |
| VerfasserIn |
C. C. Clason, D. W. F. Mair, P. W. Nienow, I. D. Bartholomew, A. Sole, S. Palmer, W. Schwanghart |
| 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 ; 9, no. 1 ; Nr. 9, no. 1 (2015-01-22), S.123-138 |
| Datensatznummer |
250116741
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| Publikation (Nr.) |
 copernicus.org/tc-9-123-2015.pdf |
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| Zusammenfassung |
| Meltwater delivered to the bed of the Greenland Ice Sheet is a driver of
variable ice-motion through changes in effective pressure and enhanced basal
lubrication. Ice surface velocities have been shown to respond rapidly both
to meltwater production at the surface and to drainage of supraglacial
lakes, suggesting efficient transfer of meltwater from the supraglacial to
subglacial hydrological systems. Although considerable effort is currently
being directed towards improved modelling of the controlling surface and
basal processes, modelling the temporal and spatial evolution of the
transfer of melt to the bed has received less attention. Here we present the
results of spatially distributed modelling for prediction of moulins and
lake drainages on the Leverett Glacier in Southwest Greenland. The model is
run for the 2009 and 2010 ablation seasons, and for future increased melt
scenarios. The temporal pattern of modelled lake drainages are qualitatively
comparable with those documented from analyses of repeat satellite imagery.
The modelled timings and locations of delivery of meltwater to the bed also
match well with observed temporal and spatial patterns of ice surface speed-ups. This is particularly true for the lower catchment (<1000 m a.s.l.)
where both the model and observations indicate that the development
of moulins is the main mechanism for the transfer of surface meltwater to
the bed. At higher elevations (e.g. 1250–1500 m a.s.l.) the development and
drainage of supraglacial lakes becomes increasingly important. At these
higher elevations, the delay between modelled melt generation and subsequent
delivery of melt to the bed matches the observed delay between the peak air
temperatures and subsequent velocity speed-ups, while the instantaneous
transfer of melt to the bed in a control simulation does not. Although both
moulins and lake drainages are predicted to increase in number for future
warmer climate scenarios, the lake drainages play an increasingly important
role in both expanding the area over which melt accesses the bed and in
enabling a greater proportion of surface melt to reach the bed. |
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