HR: 13:40h
AN: C43A-01 INVITED    [Abstracts]
TI: A first calving law for ice shelves: spreading-rate control of calving rate
AU: * Alley, R B
EM: rba6@psu.edu
AF: Department of Geosciences and PSICE, Pennsylvania State University, Deike Building, University Park, PA 16802, United States
AU: Joughin, I
EM: ian@apl.washington.edu
AF: Polar Science Center, Applied Physics Lab, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, United States
AU: Horgan, H J
EM: hhorgan@geosc.psu.edu
AF: Department of Geosciences and PSICE, Pennsylvania State University, Deike Building, University Park, PA 16802, United States
AU: Dupont, T K
EM: tdupont@uci.edu
AF: Department of Earth System Science, University of California Irvine, Croul Hall, Irvine, CA 92697, United States
AU: Parizek, B R
EM: parizek@geosc.psu.edu
AF: Department of Geosciences and PSICE, Pennsylvania State University, Deike Building, University Park, PA 16802, United States
AU: Anandakrishnan, S
EM: sak@geosc.psu.edu
AF: Department of Geosciences and PSICE, Pennsylvania State University, Deike Building, University Park, PA 16802, United States
AU: Cuffey, K M
EM: kcuffey@berkeley.edu
AF: Department of Geography, University of California Berkeley, 507 McCone Hall, Berkeley, CA 94720,
AB: The rate of iceberg production from floating, cold ice shelves increases with the along-flow spreading rate near the ice-shelf front, based on a curve-fit to preliminary data from several ice shelves. Although calving almost certainly depends on many forcings, ice-shelf properties, and pre-existing flaws, we suggest that the spreading rate of the ice is the most important control (that is, the rate at which ice shelves fall apart is controlled primarily by their tendency to fall apart). We obtain calving rate from near-frontal velocity assuming steady state, and strain rate from the velocity gradient, focusing on central flowlines of ice shelves. A best-fit relation explains a significant and important fraction of the variance in the data set, motivating further investigation. Implementing this calving relation in models will typically produce instability in the absence of buttressing, consistent with many observations on ice shelves.
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0732 Icebergs
DE: 0774 Dynamics
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: 2007 Fall Meeting