Stress balances of ice streams in a vertically integrated, higher-order formulation
Stress balances of ice streams in a vertically integrated, higher-order formulation
复制标题
垂直集成的高阶公式中冰流的应力平衡
DOI：
10.3189/2013jog12j140
复制
发表时间：
2013
影响因子：
3.4
通讯作者：
A. C. Fowler
中科院分区：
文献类型：
--
作者：
T. Kyrke;Richard F. Katz;A. C. Fowler
摘要提高我们对冰流动力学的理解的一个挑战是建立从冰盖到冰流流动的时空过渡模型。我们解决这一问题，一个新的，垂直整合，高阶制定冰盖动力学，捕捉领先的物理低纵横比，粘性流体流动，无论在床上的滑动量。该理论引入了一个参数λ，它近似于基础应力与剪应力尺度的比率，提供了滑动和内部变形相对重要性的度量。我们的模型能够同时描述一个缓慢移动的表和快速流动的冰流的动态。为了测试配方，我们采用了三值滑动法的基本边界条件，并获得数值解，可以与以前的工作。我们调查的敏感性的流态和剪切边缘宽度参数变化，推导出后者的缩放。我们还考虑了一个双值滑动法，它强制执行一个恒定的，低的基底应力下的冰流。所得应力场的比较说明了不同的应力平衡，可以维持冰流流动。
Abstract One challenge in improving our understanding of ice-stream dynamics is to develop models of the spatial and temporal transition from ice-sheet to ice-stream flow. We address this with a new, vertically integrated, higher-order formulation for ice-sheet dynamics that captures the leading-order physics of low aspect ratio, viscous fluid flow, regardless of the amount of slip at the bed. The theory introduces a parameter, λ, which approximates the ratio of the basal stress to the shear stress scale, providing a measure of the relative importance of sliding and internal deformation. Our model is able to simultaneously describe the dynamics of both a slow-moving sheet and rapidly flowing ice streams. To test the formulation, we apply a triple-valued sliding law as the basal boundary condition and obtain numerical solutions that can be compared with previous work. We investigate the sensitivity of flow regimes and shear margin width to parameter variation, deriving a scaling for the latter. We also consider a double-valued sliding law, which enforces a constant, low basal stress beneath the ice stream. Comparisons of the resultant stress fields illustrate the different stress balances that can maintain ice-stream flow.