Abstract

Mapping the grounding zone of the Amery Ice Shelf, East Antarctica using InSAR, MODIS and ICESat

Helen Amanda Fricker
Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0225, USA.

Richard Coleman
Centre for Marine Science, University of Tasmania, Private Bag 78, Hobart, Tasmania, 7001, Australia.
Antarctic Climate and Ecosystems CRC, Hobart, Australia.
CSIRO Marine and Atmospheric Research, Hobart, Australia.

Laurie Padman
Earth & Space Research, 3350 SW Cascade Ave., Corvallis, OR 97333-1536, USA.

Ted A. Scambos
National Snow and Ice Data Center, CIRES, Campus Box 449; 1540 30th St., University of Colorado, Boulder, CO 80309-0449, USA.

Jennifer Bohlander
National Snow and Ice Data Center, CIRES, Campus Box 449; 1540 30th St., University of Colorado, Boulder, CO 80309-0449, USA.

Kelly M. Brunt
Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0225, USA.




We use a combination of satellite techniques, including differential interferometric synthetic aperture radar (InSAR), visible-band imagery from MODIS, and ICESat laser altimetry to develop a benchmark map for the AIS GZ, including its islands and ice rises. The map includes locations for the landward and seaward edges of the ice shelf flexure boundary where it is possible to identify these limits (~55% and ~30% of the AIS perimeter respectively) and the break-in-slope as an estimate of grounding line location for the entire AIS. Vertical ice motion detected with GPS provides verification of the satellite-derived GZ in two regions. Our map redefines the southwestern extremity of the floating ice and identifies several grounded regions, including five small ice rises near the ice front which contribute to understanding the stresses supporting the current dynamical state of the shelf. We also locate points, near Gillock Island, which were ephemerally grounded in 1995/6. Finally, we identify two along-flow channels in the sub-shelf topography, approximately 10 km apart, 1.5 km wide and 300-500 m high, in the area near the southern grounding zone. These channels form at the confluences of adjacent ice streams, and may play a significant role in setting the integrity of the ice shelf and steering sub-ice-shelf ocean circulation.






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