Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall
Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall
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DOI：
10.1038/ngeo2482
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发表时间：
2015-08-01
影响因子：
18.3
通讯作者：
Hubbard, Bryn
中科院分区：
文献类型：
--
作者：
Doyle, Samuel H.;Hubbard, Alun;Hubbard, Bryn
强降雨事件通过加速融化、冰流加速和冰下沉积物侵蚀对阿尔卑斯山和阿拉斯加冰川产生重大影响，但尚未评估其对格陵兰冰盖的影响。在这里，我们提出的测量冰速度，冰下水压力和气象变量从格陵兰冰盖的西部边缘在一个星期的温暖，潮湿的气旋天气在2011年8月下旬和9月初。我们发现，极端的地表径流融化和降雨导致了广泛的加速冰流延伸到140公里的冰盖内部。我们认为，季末的时间是至关重要的，在促进快速径流在一个广泛的裸露的冰面，压倒了冰下水文系统过渡到一个效率较低的冬季模式。再分析数据显示，在此期间，格陵兰岛南部和西部普遍存在类似的气旋天气条件，我们在这些地区所有有数据可查的陆地和海洋终端冰川上观察到了相应的冰流响应。考虑到未来几十年格陵兰上空温暖潮湿的空气和降雨的平流预计将变得更加频繁，我们的研究结果预示着格陵兰冰盖对气候变化的脆弱性。
Intense rainfall events significantly affect Alpine and Alaskan glaciers through enhanced melting, ice-flow acceleration and subglacial sediment erosion, yet their impact on the Greenland ice sheet has not been assessed. Here we present measurements of ice velocity, subglacial water pressure and meteorological variables from the western margin of the Greenland ice sheet during a week of warm, wet cyclonic weather in late August and early September 2011. We find that extreme surface runoff from melt and rainfall led to a widespread acceleration in ice flow that extended 140 km into the ice-sheet interior. We suggest that the late-season timing was critical in promoting rapid runoff across an extensive bare ice surface that overwhelmed a subglacial hydrological system in transition to a less-efficient winter mode. Reanalysis data reveal that similar cyclonic weather conditions prevailed across southern and western Greenland during this time, and we observe a corresponding ice-flow response at all land- and marine-terminating glaciers in these regions for which data are available. Given that the advection of warm, moist air masses and rainfall over Greenland is expected to become more frequent in the coming decades, our findings portend a previously unforeseen vulnerability of the Greenland ice sheet to climate change.