New gravity-derived bathymetry for the Thwaites, Crosson, and Dotson ice shelves revealing two ice shelf populations
New gravity-derived bathymetry for the Thwaites, Crosson, and Dotson ice shelves revealing two ice shelf populations
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DOI：
10.5194/tc-14-2869-2020
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发表时间：
2020-09-09
期刊：
影响因子：
5.2
通讯作者：
Paden, John D.
中科院分区：
文献类型：
--
作者：
Jordan, Tom A.;Porter, David;Paden, John D.
冰架通过其支撑作用在冰盖的长期稳定性中发挥着关键作用。底层测深和空腔厚度是模拟未来冰盖演化的关键输入。然而，直接观察冰架下测深非常耗时，在逻辑上存在风险，而且在某些地区根本不可能。在这里，我们使用机载和海洋重力、雷达深度探测和条带测深的新汇编来提供对快速变化的西南极洲思韦茨冰川外侧以及邻近的多特森和克罗森冰架下方的冰架下测深的新估计。该地区特别令人感兴趣，因为思韦茨冰川系统的低洼内陆逆坡使其容易受到海洋冰盖不稳定的影响，自 1993 年以来观察到的接地线快速后退表明这一过程可能正在发生。我们的研究结果证实，一条超过 800m 深的主要海洋航道延伸数十公里至思韦茨冰川前端，而邻近的冰架下方则有更复杂的水深测量。我们的新测深数据与冰架吃水深度的比较表明，自 1993 年以来形成的冰架由一个独特的群体组成，其中吃水深度与底层测深数据非常一致，这与旧冰架不同，旧冰架显示出更均匀的冰基深度。这表明，尽管某些地区的基底快速融化，但这些最近漂浮的冰架部分尚未与其后退的接地线位置和底层海洋系统达到动态平衡，这一因素必须纳入该地区未来演化模型中。
Ice shelves play a critical role in the long-term stability of ice sheets through their buttressing effect. The underlying bathymetry and cavity thickness are key inputs for modelling future ice sheet evolution. However, direct observation of sub-ice-shelf bathymetry is time-consuming, logistically risky, and in some areas simply not possible. Here we use new compilations of airborne and marine gravity, radar depth sounding, and swath bathymetry to provide new estimates of sub-ice-shelf bathymetry outboard of the rapidly changing West Antarctic Thwaites Glacier and beneath the adjacent Dotson and Crosson ice shelves. This region is of special interest, as the low-lying inland reverse slope of the Thwaites Glacier system makes it vulnerable to marine ice sheet instability, with rapid grounding line retreat observed since 1993 suggesting this process may be underway. Our results confirm a major marine channel > 800m deep extends tens of kilometres to the front of Thwaites Glacier, while the adjacent ice shelves are underlain by more complex bathymetry. Comparison of our new bathymetry with ice shelf draft reveals that ice shelves formed since 1993 comprise a distinct population where the draft conforms closely to the underlying bathymetry, unlike the older ice shelves, which show a more uniform depth of the ice base. This indicates that despite rapid basal melting in some areas, these recently floated parts of the ice shelf are not yet in dynamic equilibrium with their retreated grounding line positions and the underlying ocean system, a factor which must be included in future models of this region's evolution.