An improved model for tidally modulated grounding-line migration
An improved model for tidally modulated grounding-line migration
复制标题
潮汐调制接地线迁移的改进模型
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
G. H. Gudmundsson
中科院分区：
文献类型：
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作者：
Victor C. Tsai;G. H. Gudmundsson
了解接地线动力学是必要的长期冰盖稳定性的预测。然而，尽管越来越多的观察到潮汐对接地线迁移的影响，这种短时间尺度的迁移知之甚少，大多数建模尝试假设梁理论来计算位移。在这里，我们提出了一个改进的模型，潮汐接地线迁移，将迁移作为一个弹性断裂问题，迫使额外的海洋水压力从潮汐。这个新的模型预测，接地线不能被假定为在流体静力平衡，而且，迁移是固有的不对称和非线性，迁移距离不成比例的潮汐负荷。具体而言，对于恒定的表面坡度，接地线向上游迁移大约十倍以上的潮汐上升从平均海平面到高潮比它迁移下游的潮汐福尔斯从平均海平面到低潮，迁移距离远大于简单的浮选参数建议。数值试验还表明，在一定范围内，迁移距离对弹性模量和冰盖厚度的依赖性与梁理论的预测不一致。最后，应用新的模型在南极洲的观测结果在新的估计床坡度，虽然这些估计仍然是不确定的，由于相关的流变参数的知识不完善。
Understanding grounding-line dynamics is necessary for predictions of long-term ice-sheet stability. However, despite growing observations of the tidal influence on grounding-line migration, this short-timescale migration is poorly understood, with most modeling attempts assuming beam theory to calculate displacements. Here we present an improved model of tidal grounding-line migration that treats migration as an elastic fracture problem, forced by the additional ocean water pressure from the tide. This new model predicts that the grounding line cannot be assumed to be in hydrostatic equilibrium and, furthermore, that migration is inherently asymmetric and nonlinear, with migration distances that are not proportional to the tidal load. Specifically, for constant surface slope, the grounding line migrates upstream approximately ten times further as the tide rises from mean sea level to high tide than it migrates downstream as the tide falls from mean sea level to low tide, and migration distances are substantially larger than simple flotation arguments suggest. Numerical tests also show that the dependence of migration distance on elastic moduli and ice-sheet thickness are inconsistent with predictions of beam theory for a range of realistic values. Finally, applying the new model to observations in Antarctica results in new estimates of bed slopes, though these estimates remain uncertain due to imperfect knowledge of the relevant rheological parameters.
影响因子：
30.7
作者：
Favier, L.;Durand, G.;Le Brocq, A. M.
通讯作者：
Le Brocq, A. M.
影响因子：
5.2
作者：
Gudmundsson, G. H.;Krug, J.;Gagliardini, O.
通讯作者：
Gagliardini, O.