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Channelization of plumes beneath ice shelves

Published online by Cambridge University Press:  11 November 2015

M. C. Dallaston ,
I. J. Hewitt  and
A. J. Wells
M. C. Dallaston
Affiliation:
Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
I. J. Hewitt
Affiliation:
Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
A. J. Wells
Affiliation:
Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford OX1 3PU, UK
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Abstract

We study a simplified model of ice–ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

JFM classification

Geophysical and Geological Flows: Geophysical and Geological Flows Geophysical and Geological Flows: Ice sheets Phase change: Morphological instability
Type
Papers
Information
Journal of Fluid Mechanics , Volume 785 , 25 December 2015 , pp. 109 - 134
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Copyright
© 2015 Cambridge University Press 

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