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A boundary layer model for ice stream margins

Published online by Cambridge University Press:  18 September 2015

M. Haseloff ,
C. Schoof  and
O. Gagliardini
M. Haseloff*
Affiliation:
Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
C. Schoof
Affiliation:
Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
O. Gagliardini
Affiliation:
CNRS, LGGE, UMR5183, 38041 Grenoble, France Université de Grenoble Alpes, LGGE, UMR5183, 38041 Grenoble, France Institut Universitaire de France, Paris, France
*
†Email address for correspondence: mhaseloff@eos.ubc.ca
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Abstract

The majority of Antarctic ice is discharged via long and narrow fast-flowing ice streams. At ice stream margins, the rapid transition from the vertical shearing flow in the ice ridges surrounding the stream to a rapidly sliding plug flow in the stream itself leads to high stress concentrations and a velocity field whose form is non-trivial to determine. In this paper, we develop a boundary layer theory for this narrow region separating a lubrication-type ice ridge flow and a membrane-type ice stream flow. This allows us to derive jump conditions for the outer models describing ridge and stream self-consistently. Much of our focus is, however, on determining the velocity and shear heating fields in the margin itself. Ice stream margins have been observed to change position over time, with potentially significant implications for ice stream discharge. Our boundary layer model allows us to extend previous work that has determined rates of margin migration from a balance between shear heating in the margin and the cooling effect of margin migration into the colder ice of the surrounding ice ridge. Solving for the transverse velocity field in the margin allows us to include the effect of advection due to lateral inflow of ice from the ridge on margin migration, and we demonstrate that this reduces the rate of margin migration, as previously speculated.

JFM classification

Boundary Layers: Boundary Layers Geophysical and Geological Flows: Geophysical and Geological Flows Geophysical and Geological Flows: Ice sheets
Type
Papers
Information
Journal of Fluid Mechanics , Volume 781 , 25 October 2015 , pp. 353 - 387
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Copyright
© 2015 Cambridge University Press 

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