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Iceberg calving and ice melange rheology

University of British Columbia, Vancouver
Supervisor: Christian Schoof
Co-supervisors: Bruno Tremblay (McGill U., Montreal) and Martin Losch (AWI, Bremerhaven)

Project description:

An appreciable fraction of mass loss from the Greenland ice sheet and smaller ice caps in the Arctic occurs through the calving of icebergs at marine-terminating outlet glaciers. The calving of icebergs also affects the extent of floating ice tongues and therefore their buttressing effect on ice flow across the grounding line, which ultimately controls the sea level contribution from the grounded ice sheet or ice cap. Even after calving, icebergs and smaller ice fragments combined with seasonal sea ice in a mixture known as `ice melange' can affect the flow of outlet glaciers, as has been documented in detail at Jakobshavn Isbrae.

The capacity to model calving and the effects of ice melange are limited. In previous work on calving, there exists a substantial gap between the process-based studies of Pralong and Funk (2005) on damage mechanics and Bassis and Jacobs (2013) on elastic fracture on one hand, and models capable of describing large-scale ice dynamics such as Albrecht and Levermann (2012). The state of ice melange modelling is even more rudimentary, with as yet no dynamic continuum model available.

This project will address both, calving and ice melange modelling, with a view to incorporating them into larger-scale models and understanding the long-term dynamic effects of calving and ice melange.

To improve calving models, the asymptotic techniques of matched asymptotic expansions and multiple scales expansions will be used to bridge the gap between the local process physics of damage mechanics included in ice flow codes such as Elmer-Ice, and the requirements of larger scale ice dynamics simulations, by isolating and solving local physics offline and rigorously deriving process-based descriptions of fracturing for use at the large scale.

Ice melange bears many similarities with sea ice, consisting of a granular-like assembly of fragments of ice that can support stresses under compression but less so under tension. The project will investigate the use of sea ice rheological models that capture this behaviour using plastic yield criteria for the description of ice melange and its effect on floating ice tongues. Hopefully, some of the methodology proposed above to isolate localized effects in calving can also be brought to bear on ice melange and sea ice modelling, to improve representation of such effects as shear bands in ice melange and rifts in sea ice.


Additional information:

Required qualifications: background in physics, applied math, geophysics, oceanography or related discipline with some experience in numerical solution of partial differential equations.

The candidate is expected to spend time interacting with the co-advisors in Montreal and in Germany.



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UQAM Memorial University of Newfoundland University of Alberta
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