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Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
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Preprints
https://doi.org/10.5194/gmd-2020-131
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-2020-131
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: development and technical paper 25 May 2020

Submitted as: development and technical paper | 25 May 2020

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A revised version of this preprint was accepted for the journal GMD and is expected to appear here in due course.

Improvements in one-dimensional grounding-line parameterizations in an ice-sheet model with lateral variations

David Pollard1 and Robert DeConto2 David Pollard and Robert DeConto
  • 1Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA
  • 2Department of Geosciences, University of Massachusetts, Amherst, MA 01003, USA

Abstract. The use of a boundary-layer parameterization of buttressing and ice flux across grounding lines in a two-dimensional ice-sheet model is improved by allowing general orientations of the grounding line. This and another modification to the model's grounding-line parameterization are assessed in two settings: a narrow fjord-like domain (MISMIP+), and in future simulations of West Antarctic ice retreat under RCP8.5-based climates. The new modifications are found to have significant effects on the fjord results, which are now within the envelopes of other models in the MISMIP+ intercomparison. In contrast, the modifications have little effect on West Antarctic retreat, presumably because dynamics in the wider major Antarctic basins are adequately represented by the model's previous simpler one-dimensional formulation. As future grounding lines retreat across very deep bedrock topography in the West Antarctic simulations, buttressing is weak and deviatoric stress measures exceed the ice yield stress, implying that structural failure at these grounding lines would occur. We suggest that these grounding-line quantities should be examined in similar projections by other ice models, to better assess the potential for future structural failure.

David Pollard and Robert DeConto

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

David Pollard and Robert DeConto

David Pollard and Robert DeConto

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Latest update: 24 Nov 2020
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Short summary
Buttressing by floating ice shelves at ice-sheet grounding lines is an important process that affects ice retreat, and whether structural failure occurs in deep bathymetry. Here we use a simple algorithm to better represent 2-D grounding-line curvature in an ice-sheet model. Along with other enhancements, this improves the performance in idealized-fjord intercomparisons, and enables better diagnosis of potential structural failure at future retreating Antarctic grounding lines.
Buttressing by floating ice shelves at ice-sheet grounding lines is an important process that...
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