Seismic evidence for complex sedimentary control of Greenland Ice Sheet flow.
Seismic evidence for complex sedimentary control of Greenland Ice Sheet flow.
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DOI：
10.1126/sciadv.1603071
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发表时间：
2017-08
期刊：
影响因子：
13.6
通讯作者：
Jones GA
中科院分区：
文献类型：
--
作者：
Kulessa B;Hubbard AL;Booth AD;Bougamont M;Dow CF;Doyle SH;Christoffersen P;Lindbäck K;Pettersson R;Fitzpatrick AAW;Jones GA
地震资料表明，冰下沉积物滑移导致格陵兰冰盖对气候变暖的复杂流动响应。近几十年来，格陵兰冰盖的陆地终止边缘已经放缓，尽管其原因和对未来冰流的影响尚不清楚。最初由一种自我调节机制解释，即随着排水效率从低到高，基面滑移减少，最近的数值模拟调用了沉积控制冰盖流动作为另一种假设。尽管这两种假说都可以解释最近的冰流放缓，但它们各自对长期减速与冰流加速的预测是相互矛盾的。我们给出了振幅随角度变化的地震数据，作为对替代假说的第一次观测检验。根据我们的数值模型，我们记录了通过冰上湖泊的快速冰下排水对基础沉积物强度的瞬时修改，根据我们的数值模型，冰上湖泊是控制夏季冰盖流动的主要水流。我们的观测结果与最初的流域后沉积物减弱和冰流加速，以及随后的沉积物再强化和冰流减速的模拟一致，从而证实了另一种假说。尽管模拟的融化季节冰川下沉积物减弱导致的冰流加速目前还没有超过自我调节所迫使的冬季放缓，但从长远来看，它们可能会占据主导地位。因此，必须绘制格陵兰冰盖下的冰下沉积物的地图并确定其特征，必须对照相互竞争的自我调节机制来评估对冰流的沉积控制。
Seismic data show that subglacial sediment slip causes a complex flow response of the Greenland Ice Sheet to climate warming. The land-terminating margin of the Greenland Ice Sheet has slowed down in recent decades, although the causes and implications for future ice flow are unclear. Explained originally by a self-regulating mechanism where basal slip reduces as drainage evolves from low to high efficiency, recent numerical modeling invokes a sedimentary control of ice sheet flow as an alternative hypothesis. Although both hypotheses can explain the recent slowdown, their respective forecasts of a long-term deceleration versus an acceleration of ice flow are contradictory. We present amplitude-versus-angle seismic data as the first observational test of the alternative hypothesis. We document transient modifications of basal sediment strengths by rapid subglacial drainages of supraglacial lakes, the primary current control on summer ice sheet flow according to our numerical model. Our observations agree with simulations of initial postdrainage sediment weakening and ice flow accelerations, and subsequent sediment restrengthening and ice flow decelerations, and thus confirm the alternative hypothesis. Although simulated melt season acceleration of ice flow due to weakening of subglacial sediments does not currently outweigh winter slowdown forced by self-regulation, they could dominate over the longer term. Subglacial sediments beneath the Greenland Ice Sheet must therefore be mapped and characterized, and a sedimentary control of ice flow must be evaluated against competing self-regulation mechanisms.
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格陵兰冰下排水演化受河床弱连接区域的调节。
影响因子：
16.6
作者：
通讯作者：
--
DOI：
10.1002/2014jf003333
发表时间：
2015-06
期刊：
Journal of geophysical research. Earth surface
影响因子：
--
作者：
Dow CF;Kulessa B;Rutt IC;Tsai VC;Pimentel S;Doyle SH;van As D;Lindbäck K;Pettersson R;Jones GA;Hubbard A
通讯作者：
Hubbard A
影响因子：
3.4
作者：
Iverson, Neal R.
通讯作者：
Iverson, Neal R.
影响因子：
5.8
作者：
Cowton, T.;Nienow, P.;Mair, D.
通讯作者：
Mair, D.
影响因子：
3.4
作者：
Fitzpatrick, Andrew A. W.;Hubbard, Alun;Jones, Glenn A.
通讯作者：
Jones, Glenn A.