Evolution of basal crevasses links ice shelf stability to ocean forcing

Bassis, J. N.; Ma, Y.

doi:10.1016/j.epsl.2014.11.003

Cited by 76 publications

(148 citation statements)

References 38 publications

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“…Future work needs to be devoted to examining the convergence of this feature against increased resolution. Our results, however, would be inconsistent with those developed in a theoretical perturbation formalism by Bassis and Ma (2015), wherein the dominant wavelength for boudin spacing was on the order of Ice reaching its terminal speed at the front undergoes both semi-brittle deformation and ductile deformation. Semi-brittle failure occurs where ice has previously failed (in thin spots) and further thins the floating tongue, while ice between surface cracks and bottom cracks undergoes ductile deformation.…”

Section: Discussioncontrasting

confidence: 56%

“…These differences might reflect the primary assumptions underpinning the two approaches -one is viscous (although it allows for a brittle limit), and the other is semi-brittle. Further, the formulation developed by Bassis and Ma (2015) permits a central role for basal melting within basal crevasses, an undoubtedly crucial feature that DES does not implement in a sophisticated way at present. Care should be taken in extrapolating results here to real glaciers; these experiments are performed only as an initial exploration of the potential for this kind of rheological framework to aid in understanding patterns of flow and failure seen in nature.…”

Section: Discussionmentioning

confidence: 99%

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Semi-brittle rheology and ice dynamics in DynEarthSol3D

et al. 2017

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Abstract. We present a semi-brittle rheology and explore its potential for simulating glacier and ice sheet deformation using a numerical model, DynEarthSol3D (DES), in simple, idealized experiments. DES is a finite-element solver for the dynamic and quasi-static simulation of continuous media. The experiments within demonstrate the potential for DES to simulate ice failure and deformation in dynamic regions of glaciers, especially at quickly changing boundaries like glacier termini in contact with the ocean. We explore the effect that different rheological assumptions have on the pattern of flow and failure. We find that the use of a semibrittle constitutive law is a sufficient material condition to form the characteristic pattern of basal crevasse-aided pinchand-swell geometry, which is observed globally in floating portions of ice and can often aid in eroding the ice sheet margins in direct contact with oceans.

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Section: Discussioncontrasting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Semi-brittle rheology and ice dynamics in DynEarthSol3D

et al. 2017

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“…Models in this category (Nick et al, 2010(Nick et al, , 2013Cook et al, 2014) compute crevasse depth based on instantaneous fields and hence do not take into account the stress history in the development of fractures. Models in the second category use a continuum damage mechanics (CDM) approach, which treats calving as a continuum process that develops from microscale cracks to macroscale crevasses, and damage has an effect on the viscous behaviour of ice flow (Pralong and Funk, 2005;Jouvet et al, 2011;Duddu and Waisman, 2012;Borstad et al, 2012Borstad et al, , 2013Albrecht and Levermann, 2014;Krug et al, 2014;Bassis and Ma, 2015).…”

Section: Introductionmentioning

confidence: 99%

Ice shelf fracture parameterization in an ice sheet model

et al. 2017

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Abstract. Floating ice shelves exert a stabilizing force onto the inland ice sheet. However, this buttressing effect is diminished by the fracture process, which on large scales effectively softens the ice, accelerating its flow, increasing calving, and potentially leading to ice shelf breakup. We add a continuum damage model (CDM) to the BISICLES ice sheet model, which is intended to model the localized opening of crevasses under stress, the transport of those crevasses through the ice sheet, and the coupling between crevasse depth and the ice flow field and to carry out idealized numerical experiments examining the broad impact on large-scale ice sheet and shelf dynamics. In each case we see a complex pattern of damage evolve over time, with an eventual loss of buttressing approximately equivalent to halving the thickness of the ice shelf. We find that it is possible to achieve a similar ice flow pattern using a simple rule of thumb: introducing an enhancement factor ∼ 10 everywhere in the model domain. However, spatially varying damage (or equivalently, enhancement factor) fields set at the start of prognostic calculations to match velocity observations, as is widely done in ice sheet simulations, ought to evolve in time, or grounding line retreat can be slowed by an order of magnitude.

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“…CC BY 4.0 License. been suggested by Bassis and Ma (2015). Basal melt rates are highest at the southern end of the Totten Ice Shelf (Gwyther et al, 2014) where the thicker ice shelf means that the pressure dependent melting point is reduced at the base.…”

Section: Fracture Advectionmentioning

confidence: 97%

Modelled fracture and calving on the Totten Ice Shelf

Cook¹,

Åström²,

Zwinger³

et al. 2018

Preprint

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Abstract. The Totten Ice Shelf (IS) has a large drainage basin, much of which is grounded below sea level, leaving the glacier vulnerable to retreat through the Marine Ice Shelf Instability mechanism. The ice shelf has also been shown to be sensitive to changes in calving rate, as a very small retreat of the calving front from its current position is predicted to cause a change in flow at the grounding line. Therefore understanding the processes behind calving on the Totten IS is key to predicting its future sea level rise contribution. Here we use the Helsinki Discrete Element Model (HiDEM) to show that calving on the Totten IS 15 is controlled not only by locally produced fractures at the calving front, but is also influenced by basal fractures which are likely produced at the grounding line. Our model results show that regrounding points may be key areas of basal crevasse production, and can produce basal crevasses in both an along and across flow orientation. As well as affecting calving, along flow basal crevasses at the grounding line may be a possible precursor to basal channels. We use two additional models to examine the evolution of basal fractures as they advect downstream, demonstrating that both strain and ocean melt have the 20 potential to deform narrow fractures into the broad basal features observed near the calving front. The wide range of factors which influence fracture patterns and calving on this glacier will be a challenge for predicting its future mass loss.

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Evolution of basal crevasses links ice shelf stability to ocean forcing

Cited by 76 publications

References 38 publications

Semi-brittle rheology and ice dynamics in DynEarthSol3D

Semi-brittle rheology and ice dynamics in DynEarthSol3D

Ice shelf fracture parameterization in an ice sheet model

Modelled fracture and calving on the Totten Ice Shelf

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