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Controls on calving at a large Greenland tidewater glacier: stress regime, self-organised criticality and the crevasse-depth calving law
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Suzanne Bevan ,
Thomas R. Chudley ,
Jan Åström,
Thomas Zwinger,
Samuel Cook ,
Poul Christoffersen
Journal of Glaciology, Pages: 1 - 16
Swansea University Authors:
Adrian Luckman , Suzanne Bevan
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DOI (Published version): 10.1017/jog.2023.81
Abstract
We investigate the physical basis of the crevasse-depth (CD) calving law by analysing relationships between glaciological stresses and calving behaviour at Sermeq Kujalleq (Store Glacier), Greenland. Our observations and model simulations show that the glacier has a stable position defined by a comp...
| Published in: | Journal of Glaciology |
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| ISSN: | 0022-1430 1727-5652 |
| Published: |
Cambridge University Press (CUP)
2023
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa65465 |
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| Abstract: |
We investigate the physical basis of the crevasse-depth (CD) calving law by analysing relationships between glaciological stresses and calving behaviour at Sermeq Kujalleq (Store Glacier), Greenland. Our observations and model simulations show that the glacier has a stable position defined by a compressive arch between lateral pinning points. Ice advance beyond the arch results in calving back to the stable position; conversely, if melt-undercutting forces the ice front behind the stable position, it readvances because ice velocities exceed subaqueous melt rates. This behaviour is typical of self-organising criticality, in which the stable ice-front position acts as an attractor between unstable super-critical and sub-critical regimes. This perspective provides strong support for a ‘position-law’ approach to modelling calving at Sermeq Kujalleq, because any calving ‘rate’ is simply a by-product of how quickly ice is delivered to the critical point. The CD calving law predicts ice-front position from the penetration of surface and basal crevasse fields, and accurately simulates super-critical calving back to the compressive arch and melt-driven calving into the sub-critical zone. The CD calving law reflects the glaciological controls on calving at Sermeq Kujalleq and exhibits considerable skill in simulating its mean position and seasonal fluctuations. |
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| Keywords: |
calving; glacier calving; glacier modelling |
| College: |
Faculty of Science and Engineering |
| Funders: |
Funding for satellite image analysis and modelling was
provided by NERC, grant number NE/P011365/1 CALISMO (Calving Laws
for Ice Sheet Models). Field data collection was funded by the European
Research Council as part of the RESPONDER project under the European
Union’s Horizon 2020 research and innovation program (grant 683043) and a Natural Environment Research Council Doctoral Training Partnership
Studentship held by T.R.C. (grant NE/L002507/1). |
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