Transition of flow regime along a marine-terminating outlet glacier in East Antarctica
We present results of a multi-methodological approach to characterize the flow regime of West Ragnhild Glacier, the widest glacier in Dronning Maud Land, Antarctica. A new airborne radar survey points to substantially thicker ice (>2000 m) than previously thought. With a discharge estimate of 13–...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2014-05-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/8/867/2014/tc-8-867-2014.pdf |
| _version_ | 1818573072845766656 |
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| author | D. Callens K. Matsuoka D. Steinhage B. Smith E. Witrant F. Pattyn |
| author_facet | D. Callens K. Matsuoka D. Steinhage B. Smith E. Witrant F. Pattyn |
| author_sort | D. Callens |
| collection | DOAJ |
| description | We present results of a multi-methodological approach to characterize the
flow regime of West Ragnhild Glacier, the widest glacier in Dronning Maud
Land, Antarctica. A new airborne radar survey points to substantially thicker
ice (>2000 m) than previously thought. With a discharge estimate
of 13–14 Gt yr<sup>−1</sup>, West Ragnhild Glacier thus becomes of the
three major outlet glaciers in Dronning Maud Land. Its bed topography is
distinct between the upstream and downstream section: in the downstream
section (<65 km upstream of the grounding line), the glacier
overlies a wide and flat basin well below the sea level, while the upstream
region is more mountainous. Spectral analysis of the bed topography also
reveals this clear contrast and suggests that the downstream area is sediment
covered. Furthermore, bed-returned power varies by 30 dB within
20 km near the bed flatness transition, suggesting that the water
content at bed/ice interface increases over a short distance downstream,
hence pointing to water-rich sediment. Ice flow speed observed in the
downstream part of the glacier (~250 m yr<sup>−1</sup>) can only be
explained through very low basal friction, leading to a substantial amount of
basal sliding in the downstream 65 km of the glacier. All the above
lines of evidence (sediment bed, wetness and basal motion) and the relatively
flat grounding zone give the potential for West Ragnhild Glacier to be more
sensitive to external forcing compared to other major outlet glaciers in this
region, which are more stable due to their bed geometry (e.g. Shirase
Glacier). |
| first_indexed | 2024-12-15T00:06:13Z |
| format | Article |
| id | doaj.art-10b4af6a4c14424bb748d91dfa629f48 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-15T00:06:13Z |
| publishDate | 2014-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-10b4af6a4c14424bb748d91dfa629f482022-12-21T22:42:43ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242014-05-018386787510.5194/tc-8-867-2014Transition of flow regime along a marine-terminating outlet glacier in East AntarcticaD. Callens0K. Matsuoka1D. Steinhage2B. Smith3E. Witrant4F. Pattyn5Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, BelgiumNorwegian Polar Institute, Tromsø, NorwayAlfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, GermanyApplied Physics Laboratory, University of Washington, Seattle, WA, USALaboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, BelgiumLaboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, BelgiumWe present results of a multi-methodological approach to characterize the flow regime of West Ragnhild Glacier, the widest glacier in Dronning Maud Land, Antarctica. A new airborne radar survey points to substantially thicker ice (>2000 m) than previously thought. With a discharge estimate of 13–14 Gt yr<sup>−1</sup>, West Ragnhild Glacier thus becomes of the three major outlet glaciers in Dronning Maud Land. Its bed topography is distinct between the upstream and downstream section: in the downstream section (<65 km upstream of the grounding line), the glacier overlies a wide and flat basin well below the sea level, while the upstream region is more mountainous. Spectral analysis of the bed topography also reveals this clear contrast and suggests that the downstream area is sediment covered. Furthermore, bed-returned power varies by 30 dB within 20 km near the bed flatness transition, suggesting that the water content at bed/ice interface increases over a short distance downstream, hence pointing to water-rich sediment. Ice flow speed observed in the downstream part of the glacier (~250 m yr<sup>−1</sup>) can only be explained through very low basal friction, leading to a substantial amount of basal sliding in the downstream 65 km of the glacier. All the above lines of evidence (sediment bed, wetness and basal motion) and the relatively flat grounding zone give the potential for West Ragnhild Glacier to be more sensitive to external forcing compared to other major outlet glaciers in this region, which are more stable due to their bed geometry (e.g. Shirase Glacier).http://www.the-cryosphere.net/8/867/2014/tc-8-867-2014.pdf |
| spellingShingle | D. Callens K. Matsuoka D. Steinhage B. Smith E. Witrant F. Pattyn Transition of flow regime along a marine-terminating outlet glacier in East Antarctica The Cryosphere |
| title | Transition of flow regime along a marine-terminating outlet glacier in East Antarctica |
| title_full | Transition of flow regime along a marine-terminating outlet glacier in East Antarctica |
| title_fullStr | Transition of flow regime along a marine-terminating outlet glacier in East Antarctica |
| title_full_unstemmed | Transition of flow regime along a marine-terminating outlet glacier in East Antarctica |
| title_short | Transition of flow regime along a marine-terminating outlet glacier in East Antarctica |
| title_sort | transition of flow regime along a marine terminating outlet glacier in east antarctica |
| url | http://www.the-cryosphere.net/8/867/2014/tc-8-867-2014.pdf |
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