Glaciological history and structural evolution of the Shackleton Ice Shelf system, East Antarctica, over the past 60 years
Glaciological history and structural evolution of the Shackleton Ice Shelf system, East Antarctica, over the past 60 years
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DOI：
10.5194/tc-17-157-2023
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发表时间：
2023-01
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通讯作者：
S. Thompson;B. Kulessa;A. Luckman;J. Halpin;J. Greenbaum;T. Pelle;F. Habbal;Jingxue Guo;Lenneke M. Jong;J. L. Roberts;Bo Sun;D. Blankenship
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作者：
S. Thompson;B. Kulessa;A. Luckman;J. Halpin;J. Greenbaum;T. Pelle;F. Habbal;Jingxue Guo;Lenneke M. Jong;J. L. Roberts;Bo Sun;D. Blankenship
抽象。在南极洲登曼冰川下发现了最深的冰下槽，再加上接地线处的基底融化率很高，这引起了人们对其后退脆弱性的严重关切。因此，最近的注意力一直集中在了解驱动登曼冰川的动态演变的控制。在这里，我们考虑沙克尔顿系统，包括沙克尔顿冰架，登曼冰川，以及相邻的斯科特，诺斯克利夫，罗斯科和阿普费尔冰川，其中几乎没有什么是已知的。我们扩大了以前观察到的动态变化的背景下，登曼冰川的沙克尔顿系统的更广泛的区域，在过去的7年（2015-2022）的多个十年的时间框架和改进的两年一次的时间频率的观测。我们将新的卫星观测冰结构和机载雷达数据与冰锋位置和冰流速的变化相结合，以研究系统的变化。在60年的观测期间，我们发现沙克尔顿冰架和斯科特冰川上的显著裂缝传播，以及冰架和出口冰川之间的浮动剪切边缘的显著结构变化，以及系统区域中盐浓度升高和盐水渗透的冰的特征。在2017-2022年期间，我们观察到斯科特冰川漂浮部分的冰流速显着增加（高达50%），与靠近冰锋的小规模产犊和裂缝传播相一致。我们没有观察到任何季节性变化或冰流速度在沙克尔顿系统的其余部分的显着变化。考虑到该系统的潜在脆弱性，以加速撤退到过度加深，潜在的沉积物填充的基岩槽，在沙克尔顿系统的冰川学，海洋学和地质条件的进一步了解，需要提高数值模型预测的确定性，我们确定了一些优先事项，为今后的研究。由于进入这些偏远的沿海地区是一个重大挑战，需要协调国际合作努力，以量化沙克尔顿地区在未来几个世纪可能对海平面上升的贡献。
Abstract. The discovery of Antarctica's deepest subglacial trough beneath the Denman Glacier, combined with high rates of basal melt at the grounding line, has caused significant concern over its vulnerability to retreat. Recent attention has therefore been focusing on understanding the controls driving Denman Glacier's dynamic evolution. Here we consider the Shackleton system, comprised of the Shackleton Ice Shelf, Denman Glacier, and the adjacent Scott, Northcliff, Roscoe and Apfel glaciers, about which almost nothing is known. We widen the context of previously observed dynamic changes in the Denman Glacier to the wider region of the Shackleton system, with a multi-decadal time frame and an improved biannual temporal frequency of observations in the last 7 years (2015–2022). We integrate new satellite observations of ice structure and airborne radar data with changes in ice front position and ice flow velocities to investigate changes in the system. Over the 60-year period of observation we find significant rift propagation on the Shackleton Ice Shelf and Scott Glacier and notable structural changes in the floating shear margins between the ice shelf and the outlet glaciers, as well as features indicative of ice with elevated salt concentration and brine infiltration in regions of the system. Over the period 2017–2022 we observe a significant increase in ice flow speed (up to 50 %) on the floating part of Scott Glacier, coincident with small-scale calving and rift propagation close to the ice front. We do not observe any seasonal variation or significant change in ice flow speed across the rest of the Shackleton system. Given the potential vulnerability of the system to accelerating retreat into the overdeepened, potentially sediment-filled bedrock trough, an improved understanding of the glaciological, oceanographic and geological conditions in the Shackleton system are required to improve the certainty of numerical model predictions, and we identify a number of priorities for future research. With access to these remote coastal regions a major challenge, coordinated internationally collaborative efforts are required to quantify how much the Shackleton region is likely to contribute to sea level rise in the coming centuries.