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| Titel |
Large surface meltwater discharge from the Kangerlussuaq sector of the Greenland ice sheet during the record-warm year 2010 explained by detailed energy balance observations |
| VerfasserIn |
D. As, A. L. Hubbard, B. Hasholt, A. B. Mikkelsen, M. R. Broeke, R. S. Fausto |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2012-02-13), S.199-209 |
| Datensatznummer |
250003385
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| Publikation (Nr.) |
 copernicus.org/tc-6-199-2012.pdf |
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| Zusammenfassung |
| This study uses data from six on-ice weather stations, calibrated
MODIS-derived albedo and proglacial river gauging measurements to drive and
validate an energy balance model. We aim to quantify the record-setting
positive temperature anomaly in 2010 and its effect on mass balance and
runoff from the Kangerlussuaq sector of the Greenland ice sheet. In 2010,
the average temperature was 4.9 °C (2.7 standard deviations) above the
1974–2010 average in Kangerlussuaq. High temperatures were also observed
over the ice sheet, with the magnitude of the positive anomaly increasing
with altitude, particularly in August. Simultaneously, surface albedo was
anomalously low in 2010, predominantly in the upper ablation zone. The low
albedo was caused by high ablation, which in turn profited from high
temperatures and low winter snowfall. Surface energy balance calculations
show that the largest melt excess (∼170%) occurred in the upper
ablation zone (above 1000 m), where higher temperatures and lower albedo
contributed equally to the melt anomaly. At lower elevations the melt excess
can be attributed to high atmospheric temperatures alone. In total, we
calculate that 6.6 ± 1.0 km3 of surface meltwater ran off the ice
sheet in the Kangerlussuaq catchment in 2010, exceeding the reference year
2009 (based on atmospheric temperature measurements) by ∼150%.
During future warm episodes we can expect a melt response of at least the
same magnitude, unless a larger wintertime snow accumulation delays and
moderates the melt-albedo feedback. Due to the hypsometry of the ice sheet,
yielding an increasing surface area with elevation, meltwater runoff will be
further amplified by increases in melt forcings such as atmospheric heat. |
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