Marine ice sheet dynamics: Hysteresis and neutral equilibrium

Durand, Gaël; Gagliardini, Olivier; Fleurian, Basile de; Zwinger, Thomas; Meur, E. Le

doi:10.1029/2008jf001170

Cited by 148 publications

(265 citation statements)

References 34 publications

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“…He demonstrated that (1) marine ice sheets do not exhibit neutral equilibrium, but have well-defined, discrete equilibrium profiles; (2) steady grounding lines cannot be stable on upward-sloping beds; (3) marine ice sheets with overdeepened beds can undergo hysteresis under variations in sea level, accumulation rate, basal slipperiness and ice viscosity. Robison et al (2009) confirmed the stability of the grounding line on a downward bed slope comparing fluid-mechanical experiments and model results (with time-dependent evolution of the grounding line), while Durand et al (2009a) demonstrated the instability of marine ice sheets on upsloping beds with a Full Stokes (Elmer/Ice) model.…”

Section: Introductionsupporting

confidence: 48%

“…Conversely, for MG models, changes in grounding line position are generally small and reversible. However, the models based on shallow-ice approximation used by Vieli and Payne lack a second independent boundary condition that is needed to accurately represent grounding line migration (see below ;Schoof 2007a;Durand et al 2009a), and although MG models generally produce more consistent results, a major drawback remains the complexity to implement in a threedimensional ice sheet model (Vieli and Payne 2005).…”

Section: Numerical Approachesmentioning

confidence: 99%

“…With this method, the total number of nodes is constant and only the horizontal distribution of the nodes is modified. Durand et al (2009a) need a grid size below 100 m at the grounding line in order to achieve consistent results. Goldberg et al (2009) used adaptive refinement, i.e.…”

Section: Numerical Approachesmentioning

confidence: 99%

“…Full Stokes (FS) models (Durand et al 2009a, b) solve the full system of linear momentum equations. Due to the considerable computational effort, approximations to these equations are often used, such as higher-order, shallow-shelf and shallow-ice approximations.…”

Section: Linear Momentummentioning

confidence: 99%

“…Durand et al (2009a) used the finite element code Elmer/Ice to couple the Stokes equations with the evolution of two free surfaces, i.e. the upper interface (air/ice) and the bottom interface (ice/bed or ice/ sea).…”

Section: Numerical Approachesmentioning

confidence: 99%

See 4 more Smart Citations

Representing Grounding Line Dynamics in Numerical Ice Sheet Models: Recent Advances and Outlook

Docquier¹,

Perichon²,

Pattyn³

2011

The Earth's Cryosphere and Sea Level Change

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Recent satellite observations of the Antarctic and Greenland ice sheets show accelerated ice flow and associated ice sheet thinning along coastal outlet glaciers in contact with the ocean. Both processes are the result of grounding line retreat due to melting at the grounding line (the grounding line is the contact of the ice sheet with the ocean, where it starts to float and forms an ice shelf or ice tongue). Such rapid ice loss is not yet included in large-scale ice sheet models used for IPCC projections, as most of the complex processes are poorly understood. Here we report on the state-of-the art of grounding line migration in marine ice sheets and address different ways in which grounding line migration can be attributed and represented in ice sheet models. Using onedimensional ice flow models of the ice sheet/ice shelf system we carried out a number of sensitivity experiments with different spatial resolutions and stress approximations. These are verified with semi-analytical steady state solutions. Results show that, in large-scale finite-difference models, grounding line migration is dependent on the numerical treatment (e.g. staggered/non-staggered grid) and the level of physics involved (e.g. shallow-ice/ shallow-shelf approximation).

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Section: Introductionsupporting

confidence: 48%

Section: Numerical Approachesmentioning

confidence: 99%

Section: Numerical Approachesmentioning

confidence: 99%

Section: Linear Momentummentioning

confidence: 99%

Section: Numerical Approachesmentioning

confidence: 99%

See 3 more Smart Citations

Representing Grounding Line Dynamics in Numerical Ice Sheet Models: Recent Advances and Outlook

Docquier¹,

Perichon²,

Pattyn³

2011

The Earth's Cryosphere and Sea Level Change

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Antarctic ice rise formation, evolution, and stability

Favier

Pattyn

2015

Geophysical Research Letters

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Antarctic ice rises originate from the contact between ice shelves and one of the numerous topographic highs emerging from the edge of the continental shelf. While investigations of the Raymond effect indicate their millennial‐scale stability, little is known about their formation and their role in ice shelf stability. Here we present for the first time the simulation of an ice rise using the BISICLES model. The numerical results successfully reproduce several field‐observable features, such as the substantial thinning downstream of the ice rise and the successive formation of a promontory and ice rise with stable radial ice flow center, showing that ice rises are formed during the ice sheet deglaciation. We quantify the ice rise buttressing effect, found to be mostly transient, delaying grounding line retreat significantly but resulting in comparable steady state positions. We demonstrate that ice rises are key in controlling simulations of Antarctic deglaciation.

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Atmosphere‐ocean‐ice interactions in the Amundsen Sea Embayment, West Antarctica

Turner

Orr

Gudmundsson

et al. 2017

Reviews of Geophysics

120

125

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Over recent decades outlet glaciers of the Amundsen Sea Embayment (ASE), West Antarctica, have accelerated, thinned, and retreated, and are now contributing approximately 10% to global sea level rise. All the ASE glaciers flow into ice shelves, and it is the thinning of these since the 1970s, and their ungrounding from “pinning points” that is widely held to be responsible for triggering the glaciers' decline. These changes have been linked to the inflow of warm Circumpolar Deep Water (CPDW) onto the ASE's continental shelf. CPDW delivery is highly variable and is closely related to the regional atmospheric circulation. The ASE is south of the Amundsen Sea Low (ASL), which has a large variability and which has deepened in recent decades. The ASL is influenced by the phase of the Southern Annular Mode, along with tropical climate variability. It is not currently possible to simulate such complex atmosphere‐ocean‐ice interactions in models, hampering prediction of future change. The current retreat could mark the beginning of an unstable phase of the ASE glaciers that, if continued, will result in collapse of the West Antarctic Ice Sheet, but numerical ice sheet models currently lack the predictive power to answer this question. It is equally possible that the recent retreat will be short‐lived and that the ASE will find a new stable state. Progress is hindered by incomplete knowledge of bed topography in the vicinity of the grounding line. Furthermore, a number of key processes are still missing or poorly represented in models of ice‐flow.

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Marine ice sheet dynamics: Hysteresis and neutral equilibrium

Cited by 148 publications

References 34 publications

Representing Grounding Line Dynamics in Numerical Ice Sheet Models: Recent Advances and Outlook

Representing Grounding Line Dynamics in Numerical Ice Sheet Models: Recent Advances and Outlook

Antarctic ice rise formation, evolution, and stability

Atmosphere‐ocean‐ice interactions in the Amundsen Sea Embayment, West Antarctica

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