HR: 14:10h
AN: C43A-03    [Abstracts]
TI: Ice sheet/shelf dynamics at grounding lines
AU: * Robison, R A
EM: ravr2@cam.ac.uk
AF: ITG, DAMTP, University of Cambridge, CMS, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom
AU: Huppert, H E
EM: heh1@esc.cam.ac.uk
AF: ITG, DAMTP, University of Cambridge, CMS, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom
AU: Worster, G
EM: grae@damtp.cam.ac.uk
AF: ITG, DAMTP, University of Cambridge, CMS, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom
AB: We present a novel experimental and theoretical analysis of the conditions under which an ice sheet loses contact with its basal bed rock to form a floating ice shelf. The experiments consist of modelling the ice sheet by a Newtonian viscous fluid, either glycerine or golden syrup. The `ocean' is represented by a relatively dense solution of aqueous potassium carbonate, made up to be more dense than the viscous fluid of the `ice' shelf. The viscous fluid is input just above the `ocean' surface at a constant flux to propagate in a two-dimensional fashion down an inclined ramp into the `ocean'. The grounding line, at which the viscous fluid leaves the ramp and flows over the aqueous ocean, was observed to approach a steady position dependent on the values of the flux, the bed slope, the kinematic viscosity of the viscous fluid and its density difference from the underlying `ocean'. A simple but powerful, complementary theory was developed, based on balancing horizontal forces at the grounding line, where the differing flow regimes of the ice sheet and ice shelf must match. The theoretical results for the downslope position of the grounding line are in good agreement with our experimental observations. Video sequences of the experiments will be presented.
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0738 Ice (1863)
DE: 0774 Dynamics
DE: 0798 Modeling
SC: Cryosphere [C]
MN: 2007 Fall Meeting