HR: 0800h
AN: C11B-0457    [Abstracts]
TI: The Iceberg Calving Problem: Can we Model Iceberg Calving with an Empirical Calving Law?
AU: * Bassis, J N
EM: jbassis@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, United States
AU: Fricker, H A
EM: hafricker@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, United States
AB: Iceberg calving provides an efficient mechanism to transfer large amounts of ice to the ocean in a near instantaneous fashion, thereby not only drastically changing the mass balance of a glacier/ice sheet, but the geometry of the glacial system. These changes can have a profound effect on the flow of inland ice through a variety of feedbacks. For example, removal of sections of ice can (i) reduce the back-pressure or "buttressing" of inland ice or (ii) perturb basal hydrology and alter the basal sliding conditions. Furthermore, because iceberg calving tends to be important in regions with high longitudinal stresses, the non-local nature of longitudinal stresses allows the possibility that perturbations are transmitted far into the interior of the glacier or ice sheet. Despite this important role iceberg calving is rarely implemented in large scale numerical models. As a first step, we have developed a depth-integrated flowline model that includes vertical shear, longitudinal stresses and (a parameterization of) lateral shear. The simplicity and computational efficiency of this model allows us to explore the time-dependent behavior of a variety of iceberg calving laws in combination with different basal sliding laws (for inland ice) and lateral stress regimes. We present preliminary results, using the model to evaluate the interplay between ice dynamics and a calving law in which calving occurs when the ratio of crevasse penetration depth to ice thickness exceeds a critical ratio. We find that this model exhibits a wide range of behavior ranging from cycling detachment of large tabular icebergs to steady a calving front to sudden meltwater triggered disintegration episodes.
DE: 0720 Glaciers
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0730 Ice streams
DE: 0732 Icebergs
SC: Cryosphere [C]
MN: 2007 Fall Meeting