A High-Resolution Antarctic Grounding Zone Product from ICESat-2 Laser Altimetry

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The Antarctic grounding zone, which is the transition between the fully grounded ice sheet to freely floating ice shelf, plays a critical role in ice sheet instability, mass budget calculations and ice sheet model projections. It is therefore important to continuously monitor its location and migration over time. Here we present the first ICESat-2-derived high-resolution grounding zone product of the Antarctica Ice Sheet, including three important boundaries: the inland limit of tidal flexure (Point F), inshore limit of hydrostatic equilibrium (Point H) and the break-in-slope (Point Ib). This dataset was derived from automated techniques developed in this study, using ICESat-2 laser altimetry repeat tracks between 30 March 2019 and 30 September 2020. The new grounding zone product has a near complete coverage of the Antarctica Ice Sheet with a total of 21346 Point F, 18149 Point H and 36765 Point Ib identified, including the difficult to survey grounding zones, such as the fast-flowing glaciers draining into the Amundsen Sea Embayment. The locations of newly derived ICESat-2 landward limit of tidal flexure agree well with the most recent differential synthetic aperture radar interferometry (DInSAR) observations in 2018, with the mean absolute separation and standard deviation of 0.02 and 0.02 km, respectively. By comparing the ICESat-2-derived grounding zone with the previous grounding zone products, we find up-to 15 km grounding line retreat on the Crary Ice Rise of Ross Ice Shelf and the pervasive landward grounding line migration along the Amundsen Sea Embayment during the past two decades. We also identify the presence of ice plain on the Filchner-Ronne Ice Shelf and the influence of oscillating ocean tides on the grounding zone migration. The product derived from this study is available at https://doi.org/10.5523/bris.bnqqyngt89eo26qk8keckglww (Li et al., 2021) and is archived and maintained at the National Snow and Ice Data Center.
Original languageEnglish
JournalEarth System Science Data
Publication statusSubmitted - 26 Jul 2021


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