Day 4

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Paper title Antarctic Grounding Zone Distributions and Migrations from ICESat-2 Laser Altimetry
  1. Tian Li University of Bristol, United Kingdom Speaker
  2. Geoffrey Dawson University of Bristol, United Kingdom
  3. Stephen Chuter Univeristy of Bristol
  4. Jonathan Bamber University of Bristol
Form of presentation Poster
  • A9. Polar Science and Cryosphere
    • A9.04 Mass Balance of the Cryosphere
Abstract text The Antarctic Ice Sheet is losing mass and contributing to global sea level rise at an accelerated pace. The grounding line plays a critical role in this process, as it represents the location where the ice detaches from the bedrock and floats in the ocean, which is important for the accurate determination of ice discharge from the grounded ice sheet. Accelerated mass loss from the Antarctic Ice Sheet is, in part, due to grounding line retreat. Therefore, accurate knowledge of the grounding line location and its migration over time is valuable in understanding the processes controlling mass balance, ice sheet stability and sea level contributions from Antarctica.

As a subglacial feature, the grounding line location is difficult to survey directly. However, satellite observable grounding zone features can be used as a proxy for the grounding line. Multiple Earth Observation techniques have been used to map the Antarctic grounding zone, including the Differential Synthetic Aperture Radar Interferometry (DInSAR), ICESat laser altimetry repeat-track analysis, CryoSat-2 radar altimetry crossover analysis, and brightness-based break-in-slope mapping from optical images. These methods, however, are limited by either spatial-temporal coverage or accuracy. The high-resolution laser altimetry satellite ICESat-2 has the potential to map the Antarctic grounding zone with improved coverage and accuracy. This provides a new opportunity to investigate grounding line changes and their relationship to ice dynamics at a finer resolution in both space and time.

Here we first present a new methodological framework for mapping three grounding zone features automatically from ICESat-2: the landward limit of tidal flexure Point F, the inshore limit of hydrostatic equilibrium Point H and the break-in-slope Point I_b. We then present a new high-resolution grounding zone product by applying this method to the whole Antarctic Ice Sheet. We discuss the sensitivity and accuracy of our approach by comparing with historic and contemporaneous grounding zone products. Based on this new ICESat-2-derived grounding zone product, we investigate grounding zone migration behaviour in key regions of the Antarctic Ice Sheet.