Coupled ice shelf-ocean modeling and complex grounding line retreat from a seabed ridge
Coupled ice shelf-ocean modeling and complex grounding line retreat from a seabed ridge
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DOI：
10.1002/2015jf003791
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发表时间：
2016-05-01
影响因子：
3.9
通讯作者：
Gudmundsson, G. H.
中科院分区：
文献类型：
--
作者：
De Rydt, J.;Gudmundsson, G. H.
最近的观测和模拟工作表明，南极洲的浮冰架和邻近的接地冰原之间存在着复杂的机械耦合。一个典型的例子是南极洲西部的松岛冰川，由于最近由海洋引起的冰架融化的增加，它具有很强的负质量平衡。质量损失与海底山脊的接地线后退一致，直到20世纪70年代，它至少部分接地在海底山脊上。目前，尚不清楚是什么导致了这种退缩的开始，以及海洋和冰架几何形状之间的反馈机制如何影响冰动力学。为了解决这些问题，我们提出了具有接地线解析能力的最先进的浅冰流模型与具有冰架静态实现的三维海洋环流模型之间的离线耦合的第一个结果。一系列理想化的实验模拟了海底脊的退缩，以响应海洋强迫的变化，我们表明，在20年的温暖海洋条件下，退缩变得不可逆转。与简单的与深度相关的融化速率参数化的实验比较表明，这种参数化无法捕获退缩过程的细节，并且它们在50年时间尺度上高估了40%以上的质量损失。
Recent observations and modeling work have shown a complex mechanical coupling between Antarctica's floating ice shelves and the adjacent grounded ice sheet. A prime example is Pine Island Glacier, West Antarctica, which has a strong negative mass balance caused by a recent increase in ocean-induced melting of its ice shelf. The mass loss coincides with the retreat of the grounding line from a seabed ridge, on which it was at least partly grounded until the 1970s. At present, it is unclear what has caused the onset of this retreat and how feedback mechanisms between the ocean and ice shelf geometry have influenced the ice dynamics. To address these questions, we present the first results from an offline coupling between a state-of-the-art shallow-ice flow model with grounding line resolving capabilities and a three-dimensional ocean general circulation model with a static implementation of the ice shelf. A series of idealized experiments simulate the retreat from a seabed ridge in response to changes in the ocean forcing, and we show that the retreat becomes irreversible after 20 years of warm ocean conditions. A comparison to experiments with a simple depth-dependent melt rate parameterization demonstrates that such parameterizations are unable to capture the details of the retreat process, and they overestimate mass loss by more than 40% over a 50 year timescale.