Ice-stream stability on a reverse bed slope
Ice-stream stability on a reverse bed slope
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DOI：
10.1038/ngeo1600
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发表时间：
2012-11
影响因子：
18.3
通讯作者：
S. Jamieson;A. Vieli;S. Livingstone;C. Ó. Cofaigh;C. Stokes;C. Hillenbrand;J. Dowdeswell
中科院分区：
文献类型：
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作者：
S. Jamieson;A. Vieli;S. Livingstone;C. Ó. Cofaigh;C. Stokes;C. Hillenbrand;J. Dowdeswell
海洋冰流的河床深入内陆，被认为是天生不稳定的。这种不稳定性特别令人担忧，因为南极西部和格陵兰岛的大部分海洋冰盖正在失去质量，它们的退缩可能会大大导致未来的海平面上升。然而，目前对冰流稳定性的理解受到观测记录的限制，这些记录太短，无法解决数十年到千年尺度的行为或验证数值模型。在这里，我们提出了一个动态的数值模拟南极冰流撤退，因为末次冰期最大（LGM），地球物理数据的约束，其行为是一致的地貌记录。我们发现，玛格丽特湾冰流的撤退LGM是高度非线性的，并中断了稳定的反向倾斜的床，理论预测快速不稳定的撤退。我们证明，这些瞬态稳定是由增强横向阻力的冰流缩小。我们的结论是，以及河床地形，冰流宽度和长期撤退的历史是至关重要的了解十年到百年尺度的冰流行为和海洋冰盖的脆弱性。
Marine-based ice streams whose beds deepen inland are thought to be inherently unstable,,. This instability is of particular concern because significant portions of the marine-based West Antarctic and Greenland ice sheets are losing mass and their retreat could contribute significantly to future sea-level rise,,,. However, the present understanding of ice-stream stability is limited by observational records that are too short to resolve multi-decadal to millennial-scale behaviour or to validate numerical models. Here we present a dynamic numerical simulation of Antarctic ice-stream retreat since the Last Glacial Maximum (LGM), constrained by geophysical data, whose behaviour is consistent with the geomorphological record. We find that retreat of Marguerite Bay Ice Stream following the LGM was highly nonlinear and was interrupted by stabilizations on a reverse-sloping bed, where theory predicts rapid unstable retreat. We demonstrate that these transient stabilizations were caused by enhanced lateral drag as the ice stream narrowed. We conclude that, as well as bed topography, ice-stream width and long-term retreat history are crucial for understanding decadal- to centennial-scale ice-stream behaviour and marine ice-sheet vulnerability.