Alaska Science Center
Mapping the grounding zone of Ross Ice Shelf using ICESat laser altimetry
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Product Type: Journal Article
Authors: Brunt, K. M., H. A. Fricker, L. Padman, T. A. Scambos, and S. R. O'Neel
We use laser altimeter data from the Ice, Cloud, and land Elevation Satellite (ICESat) to map the grounding zone (GZ) of the Ross Ice Shelf at 491 discrete locations where ICESat tracks cross the grounding line (GL). Ice flexure in the GZ occurs as the ice shelf responds to ocean height changes due primarily to tides. This region of flexure can be detected through ICESat repeat-track analysis since each pass is acquired at a different tidal phase, and 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. This offset often arises because the GL in other datasets is identified as coinciding with a prominent break-in-slope rather than the landward flexure limit. While the break-in-slope is usually found near the GL, in some regions it is collocated instead with the coupling line forming the upstream boundary of an ice plain, leading to large offsets in the inferred GL. We conclude that reliable and accurate mapping of the GL is most successful when based on synthesis of several satellite data sets.