HR: 0800h
AN: C51A-0104    [Abstracts]
TI: Rheology of the Brunt Ice Shelf Inferred by Data Assimilation The Role of Marine Ice
AU: * Khazendar, A
EM: ala.khazendar@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Rignot, E
EM: eric.rignot@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Larour, E
EM: eric.larour@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AB: The disintegration of ice shelves in Antarctic Peninsula over the past two decades clearly demonstrated the connection between the removal of ice shelves and the acceleration of their tributary glaciers. This enhanced flow of continental ice to the ocean contributes directly to global sea level rise and emphasizes the need for improved understanding of ice shelf evolution in a warming climate. An important, but not yet thoroughly examined, factor in ice shelf stability is the extent of marine ice presence, and its effect on shelf flow and mechanical integrity. The Brunt Ice Shelf on the east coast of the Weddell Sea presents a rare setting of rafts of meteoric ice being embedded in large, visible expanses of an ice mélange largely composed of marine ice. Different crystallographic structure and salinity and impurity contents should give marine ice a distinct rheology. In this work, we use satellite radar interferometric observations to infer the spatial distribution of the Brunt Ice Shelf ice rheology (flow law parameter B) by an inverse control method. We test the hypothesis of meteoric and marine ice bodies composing the ice shelf having different rheologies, and examine how this distribution affects ice shelf flow and its mechanical competence. We further use the inferred rheology distribution to locate the zones of weakness in the ice shelf, many of which are cut by large rifts filled with a mélange, and their influence on ice shelf stability. The outcome of this study makes it possible to better constrain the rheology of ice shelves known to have significant marine ice sections when velocity measurements are not available, while the methods applied demonstrate the importance (and difficulty) of deriving realistic rheologies to simulate ice shelf flow by numerical methods reliably. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration, Cryospheric Sciences Program.
DE: 0728 Ice shelves
DE: 0758 Remote sensing
DE: 0798 Modeling
SC: Cryosphere [C]
MN: 2007 Fall Meeting