Marine ice sheet dynamics: the impacts of ice-shelf buttressing
Marine ice sheet dynamics: the impacts of ice-shelf buttressing
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海洋冰盖动力学：冰架支撑的影响
DOI：
10.1017/jfm.2018.741
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发表时间：
2018
影响因子：
3.7
通讯作者：
S. Pegler
中科院分区：
文献类型：
--
作者：
S. Pegler
海洋冰原是大陆规模的冰川块，部分淹没在海洋中，南极和格陵兰岛的重要地区也是如此。在浮力驱动的不稳定机制下，这样的冰盖有可能发生不稳定，对未来的海平面有相当大的影响。本文及其同伴提出了在冰盖下游浮动部分（冰架）的侧向应力产生的支撑力的潜在主导控制作用下的海洋冰盖动力学的理论分析。分析揭示了冰架支撑抑制浮力驱动的冰盖崩塌的关键条件，并阐明了横向应力对接地线控制和整体冰盖结构的影响。对适当简化的准二维模型进行了积分，得到的分析结果可以快速评估给定冰盖结构的稳态平衡。建立了一个描述从零到强冰架支撑的海洋冰盖流态谱的解析平衡方程。可以确定的是，在这个光谱上的动力学表现出明显不同的流动形式和结构特征。为了提供足够的支撑，接地线应该在冰架的横向阻力控制部分与基岩相遇的地方附近，这意味着冰架对接地线的独立控制。基底应力的作用被降级为仅控制接地线上游冰盖的厚度，而对接地线本身没有明显的控制。进一步证明，侧向应力是导致冰架和接地线下游基岩之间额外的二次接触的原因，从而导致丰富多样的额外稳定状态。这些诱因产生了进一步的稳定机制，可以充分抑制接地线后退，消除不可弥补的迟滞效应。研究结果为海洋冰盖动力学的数值和观测解释提供了一个概念框架，并阐明了冰架独立控制接地线位置的方式。因此表明，要对今后几个世纪可能发生的冰架崩塌作出有把握的预测，就必须充分了解冰架流动的详细情况以及控制冰架侵蚀和解体的过程。
Marine ice sheets are continent-scale glacial masses that lie partially submerged in the ocean, as applies to significant regions of Antarctica and Greenland. Such ice sheets have the potential to destabilise under a buoyancy-driven instability mechanism, with considerable implications for future sea level. This paper and its companion present a theoretical analysis of marine ice sheet dynamics under the effect of a potentially dominant control of the buttressing force generated by lateral stresses on the downstream floating component of the ice sheet (the ice shelf). The analysis reveals critical conditions under which ice-shelf buttressing suppresses the buoyancy-driven collapse of an ice sheet and elucidates the implications of lateral stresses on grounding-line control and overall ice-sheet structure. Integrations of a suitably simplified quasi-two-dimensional model are conducted, yielding analytical results that provide a quick assessment of steady-state balances for a given ice-sheet configuration. An analytical balance equation describing the spectrum of marine ice sheet flow regimes spanning zero to strong ice-shelf buttressing is developed. It is determined that the dynamics across this spectrum exhibits markedly different flow regimes and structural characteristics. For sufficient buttressing, the grounding line occurs near to where a lateral-drag controlled section of the ice shelf meets the bedrock, implying an independent control of the grounding line by the ice shelf. The role of basal stresses is relegated to controlling only the thickness of the ice sheet upstream of the grounding line, with no significant control of the grounding line itself. It is further demonstrated that lateral stresses are responsible for inducing additional secondary contacts between the ice shelf and the bedrock downstream of the grounding line, resulting in a rich variety of additional steady states. These inducements generate a further stabilising mechanism that can fully suppress grounding-line retreat and eliminate otherwise irreparable hysteresis effects. The results provide a conceptual framework for numerical and observational interpretation of marine ice sheet dynamics, and clarifies the manner in which ice shelves can control grounding-line positions independently. It is thus indicated that a full resolution of the fine details of the flow of ice shelves and the processes controlling their erosion and disintegration is necessary for the confident forecasting of possible ice-sheet collapse over the course of the next few centuries.
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影响因子：
30.7
作者：
Favier, L.;Durand, G.;Le Brocq, A. M.
通讯作者：
Le Brocq, A. M.
影响因子：
5.2
作者：
J. Rydt;G. Gudmundsson;H. Rott;J. Bamber
通讯作者：
J. Rydt;G. Gudmundsson;H. Rott;J. Bamber
影响因子：
5.2
作者：
Gudmundsson, G. H.;Krug, J.;Gagliardini, O.
通讯作者：
Gagliardini, O.
影响因子：
5.2
作者：
Gudmundsson, G. H.
通讯作者：
Gudmundsson, G. H.