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Buoyant forces promote tidewater glacier iceberg calving through large basal stress concentrations

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1877-1887
Number of pages11
JournalCryosphere
Volume13
Issue number7
DOIs
DateAccepted/In press - 20 Jun 2019
DatePublished (current) - 11 Jul 2019

Abstract

Iceberg calving parameterisations currently implemented in ice sheet models do not reproduce the full observed range of calving behaviours. For example, though buoyant forces at the ice front are known to trigger full-depth calving events on major Greenland outlet glaciers, a multi-stage iceberg calving event at Jakobshavn Isbræ is unexplained by existing models. To explain this and similar events, we propose a notch-triggered rotation mechanism, whereby a relatively small subaerial calving event triggers a larger full-depth calving event due to the abrupt increase in buoyant load and the associated stresses generated at the ice–bed interface. We investigate the notch-triggered rotation mechanism by applying a geometric perturbation to the subaerial section of the calving front in a diagnostic flow-line model of an idealised glacier snout, using the full-Stokes, finite element method code Elmer/Ice. Different sliding laws and water pressure boundary conditions are applied at the ice–bed interface. Water pressure has a big influence on the likelihood of calving, and stress concentrations large enough to open crevasses were generated in basal ice. Significantly, the location of stress concentrations produced calving events of approximately the size observed, providing support for future application of the notch-triggered rotation mechanism in ice-sheet models.

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via Copernicus Publications at https://www.the-cryosphere.net/13/1877/2019/. Please refer to any applicable terms of use of the publisher.

    Final published version, 2 MB, PDF document

    Licence: CC BY

  • Supplementary information PDF

    Rights statement: This is the final published version of the article (version of record). It first appeared online via Copernicus Publications at https://www.the-cryosphere.net/13/1877/2019/. Please refer to any applicable terms of use of the publisher.

    Final published version, 328 KB, PDF document

    Licence: CC BY

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