Large subglacial lakes in East Antarctica at the onset of fast-flowing ice streams
Large subglacial lakes in East Antarctica at the onset of fast-flowing ice streams
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DOI：
10.1038/nature05554
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发表时间：
2007-02-22
期刊：
影响因子：
64.8
通讯作者：
Joughin, Ian
中科院分区：
文献类型：
--
作者：
Bell, Robin E.;Studinger, Michael;Joughin, Ian
水在冰盖的稳定性和冰流的形成中起着至关重要的作用。冰川下的湖水在湖泊之间流动（1）并迅速流失，造成灾难性的洪水（2）。然而，冰下湖泊影响冰盖动态的确切机制尚不清楚，大型冰下湖泊（3，4）与快速流动的冰流没有密切联系。在这里，我们使用卫星图像和冰面高程来确定一个冰下湖泊区域，其总面积与东方湖相似，位于南极洲东部恢复冰川冰流的起始区域，并由冰盖模型预测（5）。我们定义了四湖通过广泛的，平坦的，无特色的地区的冰面上的上游槽和下游脊。利用干涉合成孔径雷达（干涉合成孔径雷达）确定的冰速度，我们发现在这四个冰下湖泊的下坡边缘的280公里宽的部分的支流恢复冰川冰流的快速流动（移动在20至30米/年（-1））的开始。我们的结论是，冰下湖泊启动并保持快速的冰流通过积极修改的基础热制度的冰盖湖泊增生或通过冲刷基岩渠道定期排水事件。我们建议，冰下湖泊的作用需要考虑在冰盖质量平衡评估。
Water plays a crucial role in ice-sheet stability and the onset of ice streams. Subglacial lake water moves between lakes(1) and rapidly drains, causing catastrophic floods(2). The exact mechanisms by which subglacial lakes influence ice-sheet dynamics are unknown, however, and large subglacial lakes(3,4) have not been closely associated with rapidly flowing ice streams. Here we use satellite imagery and ice-surface elevations to identify a region of subglacial lakes, similar in total area to Lake Vostok, at the onset region of the Recovery Glacier ice stream in East Antarctica and predicted by ice-sheet models(5). We define four lakes through extensive, flat, featureless regions of ice surface bounded by upstream troughs and downstream ridges. Using ice velocities determined using interferometric synthetic aperture radar (InSAR), we find the onset of rapid flow ( moving at 20 to 30 m yr(-1)) of the tributaries to the Recovery Glacier ice stream in a 280-km-wide segment at the downslope margins of these four subglacial lakes. We conclude that the subglacial lakes initiate and maintain rapid ice flow through either active modification of the basal thermal regime of the ice sheet by lake accretion or through scouring bedrock channels in periodic drainage events. We suggest that the role of subglacial lakes needs to be considered in ice-sheet mass balance assessments.