A high-resolution Antarctic grounding zone product from ICESat-2 laser altimetry

[摘要] The Antarctic grounding zone, which is the transitionbetween the fully grounded ice sheet to freely floating ice shelf, plays acritical role in ice sheet stability, mass budget calculations, and ice sheetmodel projections. It is therefore important to continuously monitor itslocation and migration over time. Here we present the first ICESat-2-derivedhigh-resolution grounding zone product of the Antarctic Ice Sheet, includingthree important boundaries: the inland limit of tidal flexure (Point F),inshore limit of hydrostatic equilibrium (Point H), and the break in slope(Point I b ). This dataset was derived from automated techniquesdeveloped in this study, using ICESat-2 laser altimetry repeat tracksbetween 30 March 2019 and 30 September 2020. The new grounding zone producthas a near-complete coverage of the Antarctic Ice Sheet with a total of21 346 Point F, 18 149 Point H, and 36 765 Point I b locations identified, includingthe difficult-to-survey grounding zones, such as the fast-flowing glaciersdraining into the Amundsen Sea embayment. The locations of newly derivedICESat-2 landward limit of tidal flexure agree well with the most recentdifferential synthetic aperture radar interferometry (DInSAR) observationsin 2018, with a mean absolute separation and standard deviation of 0.02and 0.02 km, respectively. By comparing the ICESat-2-derived grounding zonewith the previous grounding zone products, we find a groundingline retreat of up to 15 km on the Crary Ice Rise of Ross Ice Shelf and a pervasivelandward grounding line migration along the Amundsen Sea embayment duringthe past 2 decades. We also identify the presence of ice plains on theFilchner–Ronne Ice Shelf and the influence of oscillating ocean tides on grounding zone migration. The product derived from this study is availableat https://doi.org/10.5523/bris.bnqqyngt89eo26qk8keckglww (Li et al., 2021) and is archived and maintained at theNational Snow and Ice Data Center.

[学科分类] 眼科学