Basal stress controls ice-flow variability during a surge cycle of Hagen Bræ, Greenland

Øyvind Winton; Sebastian B. Simonsen; Anne M. Solgaard; Robert McNabb; Nanna B. Karlsson

doi:10.1017/jog.2021.111

Basal stress controls ice-flow variability during a surge cycle of Hagen Bræ, Greenland

Øyvind Winton, Sebastian B. Simonsen, Anne M. Solgaard, Robert McNabb, Nanna B. Karlsson

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Abstract

Basal conditions play an essential role in the dynamics of outlet glaciers, but direct observations at the bed of glaciers are challenging to obtain. Instead, inverse methods can be used to infer basal parameters from surface observations. Here, we use a simple ice-flow model as a forward model in an inversion scheme to retrieve the spatio-temporally variable basal stress parameter for Hagen Bræ, North Greenland, from 1990 to 2020. Hagen Bræ is a surge-type glacier with up to an order of magnitude variability of winter velocities near the grounding line. We find that downstream changes in the basal stress parameter can explain most of the variation of flow velocity, and we further identify a region of high resistance ~20–40 km from the grounding line. We hypothesise that this region of high resistance plays an important role in controlling glacier discharge.

Original language	English
Pages (from-to)	1-15
Number of pages	15
Journal	Journal of Glaciology
Early online date	9 Nov 2021
DOIs	https://doi.org/10.1017/jog.2021.111
Publication status	Published online - 9 Nov 2021

Bibliographical note

Funding Information:
Ice velocity maps were produced as part of the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) using Copernicus Sentinel-1 SAR images distributed by ESA, and were provided by the Geological Survey of Denmark and Greenland (GEUS) at http://www.promice.dk . PROMICE is funded by the Geological Survey of Denmark and Greenland (GEUS) and the Danish Ministry of Climate, Energy and Utilities under the Danish Cooperation for Environment in the Arctic (DANCEA), and is conducted in collaboration with DTU Space (Technical University of Denmark) and Asiaq, Greenland. Ice velocity maps before 2015 are provided by the ESA Greenland Ice sheet CCI project ( www.esa-icesheets-greenland-cci.org ). Model output and information on how to obtain the data shown in Figures 1b and 1c are available at GEUS Dataverse (doi: 10.22008/FK2/SVMNIK). The authors thank James Lea, University of Liverpool for helpful discussions on the availability of DEMs.

Publisher Copyright:
© The Author(s), 2021. Published by Cambridge University Press.

Keywords

Arctic glaciology
glacier flow
glacier modelling
glacier surges
ice velocity

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1017/jog.2021.111Licence: CC BY-NC-ND

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Cite this

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abstract = "Basal conditions play an essential role in the dynamics of outlet glaciers, but direct observations at the bed of glaciers are challenging to obtain. Instead, inverse methods can be used to infer basal parameters from surface observations. Here, we use a simple ice-flow model as a forward model in an inversion scheme to retrieve the spatio-temporally variable basal stress parameter for Hagen Br{\ae}, North Greenland, from 1990 to 2020. Hagen Br{\ae} is a surge-type glacier with up to an order of magnitude variability of winter velocities near the grounding line. We find that downstream changes in the basal stress parameter can explain most of the variation of flow velocity, and we further identify a region of high resistance ~20–40 km from the grounding line. We hypothesise that this region of high resistance plays an important role in controlling glacier discharge.",

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author = "{\O}yvind Winton and Simonsen, {Sebastian B.} and Solgaard, {Anne M.} and Robert McNabb and Karlsson, {Nanna B.}",

note = "Funding Information: Ice velocity maps were produced as part of the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) using Copernicus Sentinel-1 SAR images distributed by ESA, and were provided by the Geological Survey of Denmark and Greenland (GEUS) at http://www.promice.dk . PROMICE is funded by the Geological Survey of Denmark and Greenland (GEUS) and the Danish Ministry of Climate, Energy and Utilities under the Danish Cooperation for Environment in the Arctic (DANCEA), and is conducted in collaboration with DTU Space (Technical University of Denmark) and Asiaq, Greenland. Ice velocity maps before 2015 are provided by the ESA Greenland Ice sheet CCI project ( www.esa-icesheets-greenland-cci.org ). Model output and information on how to obtain the data shown in Figures 1b and 1c are available at GEUS Dataverse (doi: 10.22008/FK2/SVMNIK). The authors thank James Lea, University of Liverpool for helpful discussions on the availability of DEMs. Publisher Copyright: {\textcopyright} The Author(s), 2021. Published by Cambridge University Press.",

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AU - McNabb, Robert

AU - Karlsson, Nanna B.

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Basal stress controls ice-flow variability during a surge cycle of Hagen Bræ, Greenland

Abstract

Bibliographical note

Keywords

UN SDGs

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