Abstract

Mapping the grounding zone of the Ross Ice Shelf, Antarctica, using ICESat laser altimetry

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.

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.

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.

Shad O'Neel
US Geological Survey, 4210 University Drive, Anchorage, AK 99508, USA.

We use laser altimetry from the Ice, Cloud, and land Elevation Satellite (ICESat) to map the grounding zone (GZ) of the Ross Ice Shelf, Antarctica, at 491 locations where ICESat tracks cross the grounding line (GL). Ice flexure in the GZ occurs as the ice shelf responds to short-term sea-level changes due primarily to tides. ICESat repeat-track analysis can be used to detect this region of flexure since each repeated pass is acquired at a different tidal phase; the technique provides estimates for both the landward limit of flexure and the point where the ice becomes hydrostatically balanced. We find that the ICESat-derived landward limits of tidal flexure are, in many places, offset by several km (and up to #60 km) from the GL mapped previously using other satellite methods. We discuss the reasons why different mapping methods lead to different GL estimates, including: instrument limitations; variability in the surface topographic structure of the GZ; and the presence of ice plains. We conclude that reliable and accurate mapping of the GL is most likely to be achieved when based on synthesis of several satellite datasets.