Repeat Subglacial Lake Drainage and Filling Beneath Thwaites Glacier
Repeat Subglacial Lake Drainage and Filling Beneath Thwaites Glacier
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DOI：
10.1029/2020gl089658
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发表时间：
2020-11-28
影响因子：
5.2
通讯作者：
Nagler, T.
中科院分区：
文献类型：
--
作者：
Malczyk, G.;Gourmelen, N.;Nagler, T.
活跃的冰下湖泊遍布南极洲，为了解冰下环境及其对冰盖物质平衡的影响提供了一个窗口。在这里，我们使用2010年至2019年的高分辨率测高数据显示，思韦茨冰川下的湖泊系统在2017年发生了一次大规模的活动，仅在该系统经历了一次大规模排水事件的4年后。我们的观察表明，在这两个事件之间，排水系统发生了重大变化，2017年上游流量增加，湖与湖之间的连通性加快，水在封闭系统内转移。在流域间期，实测的湖泊补给率比模拟估算值高137%，这表明驱动冰下融水产生的过程，如地热通量或基底摩擦，目前被低估了。南极冰下湖泊在冰盖动力学中起着重要作用。当冰下湖泊排水时，它们会释放出大量的水，与冰下排水系统相互作用。这里我们展示了湖泊在上一次排水事件发生后仅四年就开始排水。我们的研究结果表明，湖泊活动增加了冰下排水网络的效率。湖泊补给速率表明，基底融水产量明显高于先前的估计。有证据表明，在2013年和2017年的事件中，Thwaites冰川下的冰下湖泊在4年后的2017年开始排水和填充。在2013年和2017年的事件中，湖泊的行为、排水量、流量和排水开始的时间形成了对比
Active subglacial lakes have been identified throughout Antarctica, offering a window into subglacial environments and their impact on ice sheet mass balance. Here we use high-resolution altimetry measurements from 2010 to 2019 to show that a lake system under the Thwaites Glacier undertook a large episode of activity in 2017, only four years after the system underwent a substantial drainage event. Our observations suggest significant modifications of the drainage system between the two events, with 2017 experiencing greater upstream discharge, faster lake-to-lake connectivity, and the transfer of water within a closed system. Measured rates of lake recharge during the inter-drainage period are 137% larger than modeled estimates, suggesting processes that drive subglacial meltwater production, such as geothermal heat flux or basal friction, are currently underestimated.Plain Language Summary Antarctic subglacial lakes can play an important role in ice sheet dynamics. When subglacial lakes drain, they release large amounts of water that interact with the subglacial drainage system. Here we show lakes draining only four years after a previous drainage event. Our results suggest that lake activity increases the efficiency of the subglacial drainage network. Rates of lake recharge indicate that basal melt-water production is significantly higher than previously thought.Key PointsThere is evidence of drainage and filling of sub-glacial lakes under Thwaites Glacier in 2017, four years after previous activity There is contrasting lake behavior, drainage volume, discharge, and timing of drainage onset between the 2013 and 2017 events Observations of recharge rates suggest that modeled melt water production is underestimated