Controls on calving at a large Greenland tidewater glacier: stress regime, self-organised criticality and the crevasse-depth calving law

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...

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Vydané v:Journal of glaciology Ročník 69; číslo 278; s. 2059 - 2074
Hlavní autori: Benn, Douglas I., Todd, Joe, Luckman, Adrian, Bevan, Suzanne, Chudley, Thomas R., Åström, Jan, Zwinger, Thomas, Cook, Samuel, Christoffersen, Poul
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: Cambridge, UK Cambridge University Press 01.12.2023
Predmet:
Arches
calving
Compressive properties
Critical point
glacier calving
glacier modelling
Glaciers
Hydrology
Ice
Ice calving
Ice front
Ice fronts
Morphology
Seasonal variations
Tidewater
Velocity
Greenland
glacier modelling
calving
glacier calving
ISSN:0022-1430, 1727-5652
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Shrnutí: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.
Bibliografia:ObjectType-Article-1
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content type line 14
ISSN:0022-1430
1727-5652
DOI:10.1017/jog.2023.81