Subglacial lake activity beneath the ablation zone of the Greenland Ice Sheet
<p>Hydrologically active subglacial lakes can drain large volumes of water and sediment along subglacial pathways, affecting the motion and mass balance of ice masses and impacting downstream sediment dynamics. To date, only eight active lakes have been reported beneath the Greenland Ice Sheet...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-04-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/17/1775/2023/tc-17-1775-2023.pdf |
| Summary: | <p>Hydrologically active subglacial lakes can drain large volumes of
water and sediment along subglacial pathways, affecting the motion and mass
balance of ice masses and impacting downstream sediment dynamics. To date, only eight active lakes have been reported beneath the Greenland Ice Sheet (GrIS), and thus the understanding of their spatial distribution and
dynamic processes is still lacking. Here, using ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) ATL11 data, we identify 18 active subglacial lakes, 16 of which have not been previously reported. Multi-temporal ArcticDEM (digital elevation model of the Arctic) strip maps were used to extend the time series to verify lakes and determine their drainage history. The identification of active subglacial lakes beneath the GrIS is complicated by the occurrence of supraglacial lakes, which also fill and drain and are hypothesized to be almost co-located. We therefore used the temporal pattern of ice-surface elevation change to discriminate subglacial lakes and utilized the ability of ICESat-2 to penetrate through surface water to correct the elevation provided by the ATL11 data. A significant localized elevation anomaly (<span class="inline-formula">−16.03</span>–10.30 m yr<span class="inline-formula"><sup>−1</sup></span>) was measured in all detected
subglacial lakes after correction, revealing that six subglacial lakes are
twinned with supraglacial lakes. The active subglacial lakes have large
upstream hydrological catchments and are located near or below the
equilibrium line. Lakes have a median area of 1.20 km<span class="inline-formula"><sup>2</sup></span>, and 12 lakes
exhibited positive elevation-change rates during the ICESat-2 period. These
observations illustrate the potential for combining ICESat-2 and the
ArcticDEM to differentiate small subglacial lakes in the ablation zone and
beneath supraglacial lakes.</p> |
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| ISSN: | 1994-0416 1994-0424 |