The influence of subglacial hydrology on the flow of Kamb Ice Stream, West Antarctica
The influence of subglacial hydrology on the flow of Kamb Ice Stream, West Antarctica
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DOI：
10.1029/2012jf002570
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发表时间：
2013-03
期刊：
影响因子：
--
通讯作者：
N. Wel;P. Christoffersen;M. Bougamont
中科院分区：
文献类型：
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作者：
N. Wel;P. Christoffersen;M. Bougamont
西南极洲西普莱海岸的冰流具有复杂的流动历史，因为它们的基础运动受到随时间变化的基础条件的控制。尽管冰和耕地之间的机械相互作用已得到充分证实，但人们对基础水系统中区域性水输送的潜在影响知之甚少，这种影响直到最近才变得明显。为了研究水文和机械过程的综合影响，我们开发了水文、冰和耕作模型，其中冰流与库仑塑性耕作层和由离散管道组成的基础水系统耦合。当该模型应用于卡姆冰流（KIS）时，结果证实它能够在快速和停滞流动模式之间振荡。我们表明，当冰下管道被忽略或不延伸到接地线时，冰流的振荡行为受到基础热状态的控制。当管道延伸到接地线时，模拟的冰流振荡周期会增加，峰值速度会降低，并且如果供应的水量足够高，振荡可能最终停止。三种不同的水文状态表征了冰流的行为模式，这些状态通过接地线的条件来区分。研究发现，模拟的冰流速度会随着快慢周期振荡，通常持续数百年，但会根据水文活动而变化。我们的结果表明，考虑到其水文环境和大约 170 年的停滞，KIS 可能在本世纪重新启动。
Ice streams on the Siple Coast, West Antarctica, have a complex history of flow because their basal motion is governed by time‐varying basal conditions. Although the mechanical interaction between ice and till is well established, very little is known about the potential effect of regionally scaled water transport in a basal water system, which has only recently become apparent. To investigate the combined effect of hydrological and mechanical processes, we developed the Hydrology, Ice and Till model, in which ice flow is coupled to a Coulomb‐plastic till layer and a basal water system consisting of discrete conduits. When the model is applied to Kamb Ice Stream (KIS), results confirm that it is capable of oscillating between fast and stagnant modes of flow. We show that when subglacial conduits are disregarded or do not extend to the grounding line, the oscillatory behavior of the ice stream is governed by the basal thermal regime. When conduits extend to the grounding line, the modelled ice stream oscillation period is increased, peak speeds are reduced, and oscillations may ultimately cease if the volume of water supplied is sufficiently high. Three different hydrological states characterize the behavioral patterns of ice flow and these states are distinguished by conditions at the grounding line. Modelled ice stream velocities were found to oscillate with fast and slow periods typically lasting a few hundred years, although varying according to hydrological activity. Our results indicate that KIS could reactivate this century, given its hydrological setting and ~170 years of stagnation.