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Dynamics of viscous grounding lines

Published online by Cambridge University Press:  07 April 2010

ROSALYN A. V. ROBISON ,
HERBERT E. HUPPERT  and
M. GRAE WORSTER
ROSALYN A. V. ROBISON
Affiliation:
Institute of Theoretical Geophysics, Department of Applied Mathematics and Theoretical Physics, CMS, Wilberforce Road, Cambridge CB3 0WA, UK
HERBERT E. HUPPERT
Affiliation:
Institute of Theoretical Geophysics, Department of Applied Mathematics and Theoretical Physics, CMS, Wilberforce Road, Cambridge CB3 0WA, UK
M. GRAE WORSTER*
Affiliation:
Institute of Theoretical Geophysics, Department of Applied Mathematics and Theoretical Physics, CMS, Wilberforce Road, Cambridge CB3 0WA, UK
*
†Email address for correspondence: mgw.jfm@damtp.cam.ac.uk
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Abstract

We have used viscous fluids in simple laboratory experiments to explore the dynamics of grounding lines between marine ice sheets and the freely floating ice shelves into which they develop. We model the ice sheets as shear-dominated gravity currents, and the ice shelves as extensional gravity currents having zero shear to leading order. We consider the flow of viscous fluid down an inclined plane into a dense inviscid ‘ocean’. A fixed flux of fluid is supplied at the top of the plane, which is at ‘sea level’. The fluid forms a gravity current flowing down and attached to the plane for some distance before detaching to form a freely floating extensional current. We have derived a mathematical model of the flow that incorporates a new dynamic boundary condition for the position of the grounding line, where the gravity current loses contact with the solid base. The grounding line initially advances and eventually reaches a steady position. Good agreement between our theoretical predictions and experimental measurements and observations gives confidence in the fundamental assumptions of our model.

JFM classification

Geophysical and Geological Flows: Ice sheets Geophysical and Geological Flows: Gravity currents
Type
Papers
Information
Journal of Fluid Mechanics , Volume 648 , 10 April 2010 , pp. 363 - 380
Copyright
Copyright © Cambridge University Press 2010

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References

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Robison et al. supplementary movie

Movie 1. Experiment of a viscous sheet of golden syrup flowing down a rigid slope into a dense ocean of potassium carbonate solution. The syrup is supplied to the reservoir at the left from a container (red plastic box at top left) maintained at a constant head. Note that the sheet detaches from the slope to form a freely floating shelf at a 'grounding line' that migrates down slope before reaching a steady position. The movie is shown at five times actual speed.

Download Robison et al. supplementary movie(Video)
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