Abstract. 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 I_b). 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 I_b 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.

中文翻译：

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来自 ICESat-2 激光测高仪的高分辨率南极接地区产品

摘要。南极接地带是完全接地的冰盖到自由漂浮的冰架之间的过渡，在冰盖不稳定、质量预算计算和冰盖模型预测中起着关键作用。因此，随着时间的推移持续监控其位置和迁移非常重要。在这里，我们展示了南极冰盖的第一个 ICESat-2 衍生的高分辨率接地带产品，包括三个重要边界：潮汐弯曲的内陆极限（F 点）、静水平衡的近岸极限（H 点）和断裂-in-slope（点 I _b）。该数据集源自本研究中开发的自动化技术，使用 2019 年 3 月 30 日至 2020 年 9 月 30 日期间的 ICESat-2 激光测高重复轨迹。新的接地区产品几乎完全覆盖了南极冰盖，共有 21346 个点F, 18149 H 点和 36765 I _b点确定，包括难以调查的接地区域，例如流入阿蒙森海海湾的快速流动的冰川。新推导出的 ICESat-2 潮汐弯曲向陆极限位置与 2018 年最新的差分合成孔径雷达干涉测量 (DInSAR) 观测结果非常吻合，平均绝对间隔和标准偏差分别为 0.02 和 0.02 公里。通过将ICESat-2衍生的接地带与以前的接地带产品进行比较，我们发现罗斯冰架Crary冰隆上长达15公里的接地线后退以及沿阿蒙森海海湾普遍存在的陆上接地线迁移过去二十年。我们还确定了 Filchner-Ronne 冰架上冰原的存在以及振荡的海洋潮汐对接地带迁移的影响。源自这项研究的产品可在 https://doi.org/10.5523/bris.bnqqyngt89eo26qk8keckglww（Li 等人，2021 年）获得，并在国家冰雪数据中心存档和维护。