Surges of Harald Moltke Brae, 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...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/498832 2023-08-20T04:06:41+02:00 Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus Müller, Lukas Horwath, Martin Scheinert, Mirko Mayer, Christoph Ebermann, Benjamin Floricioiu, Dana Krieger, Lukas Rosenau, Ralf Vijay, Saurabh 2021-07-21 application/application/pdf https://hdl.handle.net/20.500.11850/498832 https://doi.org/10.3929/ethz-b-000498832 en eng Copernicus info:eu-repo/semantics/altIdentifier/doi/10.5194/tc-15-3355-2021 info:eu-repo/semantics/altIdentifier/wos/000677477800001 http://hdl.handle.net/20.500.11850/498832 doi:10.3929/ethz-b-000498832 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International The Cryosphere, 15 (7) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2021 ftethz https://doi.org/20.500.11850/49883210.3929/ethz-b-00049883210.5194/tc-15-3355-2021 2023-07-30T23:53:51Z 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. ISSN:1994-0416 ISSN:1994-0424 Article in Journal/Newspaper glacier Greenland The Cryosphere ETH Zürich Research Collection Greenland Moltke ENVELOPE(-35.000,-35.000,-78.333,-78.333) |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
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. ISSN:1994-0416 ISSN:1994-0424 |
format |
Article in Journal/Newspaper |
author |
Müller, Lukas Horwath, Martin Scheinert, Mirko Mayer, Christoph Ebermann, Benjamin Floricioiu, Dana Krieger, Lukas Rosenau, Ralf Vijay, Saurabh |
spellingShingle |
Müller, Lukas Horwath, Martin Scheinert, Mirko Mayer, Christoph Ebermann, Benjamin Floricioiu, Dana Krieger, Lukas Rosenau, Ralf Vijay, Saurabh Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus |
author_facet |
Müller, Lukas Horwath, Martin Scheinert, Mirko Mayer, Christoph Ebermann, Benjamin Floricioiu, Dana Krieger, Lukas Rosenau, Ralf Vijay, Saurabh |
author_sort |
Müller, Lukas |
title |
Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus |
title_short |
Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus |
title_full |
Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus |
title_fullStr |
Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus |
title_full_unstemmed |
Surges of Harald Moltke Brae, north-western Greenland: seasonal modulation and initiation at the terminus |
title_sort |
surges of harald moltke brae, north-western greenland: seasonal modulation and initiation at the terminus |
publisher |
Copernicus |
publishDate |
2021 |
url |
https://hdl.handle.net/20.500.11850/498832 https://doi.org/10.3929/ethz-b-000498832 |
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, 15 (7) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/tc-15-3355-2021 info:eu-repo/semantics/altIdentifier/wos/000677477800001 http://hdl.handle.net/20.500.11850/498832 doi:10.3929/ethz-b-000498832 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_doi |
https://doi.org/20.500.11850/49883210.3929/ethz-b-00049883210.5194/tc-15-3355-2021 |
_version_ |
1774717962159128576 |