Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus
Harald Moltke Bræ, a marine-terminating glacier in north-western Greenland, shows episodic surges. A recent surge from 2013 to 2019 lasted significantly longer (6 years) than previously observed surges (2–4 years) and exhibits a pronounced seasonality with flow velocities varying by 1 order of magni...
Published in: | The Cryosphere |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Copernicus Publications
2021
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Online Access: | https://doi.org/10.5194/tc-15-3355-2021 https://tc.copernicus.org/articles/15/3355/2021/tc-15-3355-2021.pdf https://doaj.org/article/65576698448d491d8b4f341e7ba7597f |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:65576698448d491d8b4f341e7ba7597f 2023-05-15T16:21:00+02:00 Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus L. Müller M. Horwath M. Scheinert C. Mayer B. Ebermann D. Floricioiu L. Krieger R. Rosenau S. Vijay 2021-07-01 https://doi.org/10.5194/tc-15-3355-2021 https://tc.copernicus.org/articles/15/3355/2021/tc-15-3355-2021.pdf https://doaj.org/article/65576698448d491d8b4f341e7ba7597f en eng Copernicus Publications doi:10.5194/tc-15-3355-2021 1994-0416 1994-0424 https://tc.copernicus.org/articles/15/3355/2021/tc-15-3355-2021.pdf https://doaj.org/article/65576698448d491d8b4f341e7ba7597f undefined The Cryosphere, Vol 15, Pp 3355-3375 (2021) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2021 fttriple https://doi.org/10.5194/tc-15-3355-2021 2023-01-22T16:46:41Z Harald Moltke Bræ, a marine-terminating glacier in north-western Greenland, shows episodic surges. A recent surge from 2013 to 2019 lasted significantly longer (6 years) than previously observed surges (2–4 years) and exhibits a pronounced seasonality with flow velocities varying by 1 order of magnitude (between about 0.5 and 10 m d−1) in the course of a year. During this 6-year period, the seasonal velocity always peaked in the early melt season and decreased abruptly when meltwater runoff was maximum. Our data suggest that the seasonality has been similar during previous surges. Furthermore, the analysis of satellite images and digital elevation models shows that the surge from 2013 to 2019 was preceded by a rapid frontal retreat and a pronounced thinning at the glacier front (30 m within 3 years). We discuss possible causal mechanisms of the seasonally modulated surge behaviour by examining various system-inherent factors (e.g. glacier geometry) and external factors (e.g. surface mass balance). The seasonality may be caused by a transition of an inefficient subglacial system to an efficient one, as known for many glaciers in Greenland. The patterns of flow velocity and ice thickness variations indicate that the surges are initiated at the terminus and develop through an up-glacier propagation of ice flow acceleration. Possibly, this is facilitated by a simultaneous up-glacier spreading of surface crevasses and weakening of subglacial till. Once a large part of the ablation zone has accelerated, conditions may favour substantial seasonal flow acceleration through seasonally changing meltwater availability. Thus, the seasonal amplitude remains high for 2 or more years until the fast ice flow has flattened the ice surface and the glacier stabilizes again. Article in Journal/Newspaper glacier Greenland The Cryosphere Unknown Greenland Moltke ENVELOPE(-35.000,-35.000,-78.333,-78.333) The Cryosphere 15 7 3355 3375 |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
geo envir |
spellingShingle |
geo envir L. Müller M. Horwath M. Scheinert C. Mayer B. Ebermann D. Floricioiu L. Krieger R. Rosenau S. Vijay Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus |
topic_facet |
geo envir |
description |
Harald Moltke Bræ, a marine-terminating glacier in north-western Greenland, shows episodic surges. A recent surge from 2013 to 2019 lasted significantly longer (6 years) than previously observed surges (2–4 years) and exhibits a pronounced seasonality with flow velocities varying by 1 order of magnitude (between about 0.5 and 10 m d−1) in the course of a year. During this 6-year period, the seasonal velocity always peaked in the early melt season and decreased abruptly when meltwater runoff was maximum. Our data suggest that the seasonality has been similar during previous surges. Furthermore, the analysis of satellite images and digital elevation models shows that the surge from 2013 to 2019 was preceded by a rapid frontal retreat and a pronounced thinning at the glacier front (30 m within 3 years). We discuss possible causal mechanisms of the seasonally modulated surge behaviour by examining various system-inherent factors (e.g. glacier geometry) and external factors (e.g. surface mass balance). The seasonality may be caused by a transition of an inefficient subglacial system to an efficient one, as known for many glaciers in Greenland. The patterns of flow velocity and ice thickness variations indicate that the surges are initiated at the terminus and develop through an up-glacier propagation of ice flow acceleration. Possibly, this is facilitated by a simultaneous up-glacier spreading of surface crevasses and weakening of subglacial till. Once a large part of the ablation zone has accelerated, conditions may favour substantial seasonal flow acceleration through seasonally changing meltwater availability. Thus, the seasonal amplitude remains high for 2 or more years until the fast ice flow has flattened the ice surface and the glacier stabilizes again. |
format |
Article in Journal/Newspaper |
author |
L. Müller M. Horwath M. Scheinert C. Mayer B. Ebermann D. Floricioiu L. Krieger R. Rosenau S. Vijay |
author_facet |
L. Müller M. Horwath M. Scheinert C. Mayer B. Ebermann D. Floricioiu L. Krieger R. Rosenau S. Vijay |
author_sort |
L. Müller |
title |
Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus |
title_short |
Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus |
title_full |
Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus |
title_fullStr |
Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus |
title_full_unstemmed |
Surges of Harald Moltke Bræ, north-western Greenland: seasonal modulation and initiation at the terminus |
title_sort |
surges of harald moltke bræ, north-western greenland: seasonal modulation and initiation at the terminus |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-3355-2021 https://tc.copernicus.org/articles/15/3355/2021/tc-15-3355-2021.pdf https://doaj.org/article/65576698448d491d8b4f341e7ba7597f |
long_lat |
ENVELOPE(-35.000,-35.000,-78.333,-78.333) |
geographic |
Greenland Moltke |
geographic_facet |
Greenland Moltke |
genre |
glacier Greenland The Cryosphere |
genre_facet |
glacier Greenland The Cryosphere |
op_source |
The Cryosphere, Vol 15, Pp 3355-3375 (2021) |
op_relation |
doi:10.5194/tc-15-3355-2021 1994-0416 1994-0424 https://tc.copernicus.org/articles/15/3355/2021/tc-15-3355-2021.pdf https://doaj.org/article/65576698448d491d8b4f341e7ba7597f |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-15-3355-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
7 |
container_start_page |
3355 |
op_container_end_page |
3375 |
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1766009011311738880 |