Model experiments on the evolution and stability of ice streams
Model experiments on the evolution and stability of ice streams
复制标题
冰流演化与稳定性模型实验
DOI：
10.3189/s0260305500013343
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发表时间：
1996
影响因子：
2.9
通讯作者：
WHILLANst
中科院分区：
文献类型：
--
作者：
Van Der Veen;WHILLANst
基于以下概念开发了一个简单的模型：在活跃的冰流上，流动阻力分为基础阻力和横向阻力。这些阻力源的相对作用由摩擦参数决定，该参数有效地描述了冰流下床层的强度。基础强度的降低是由融水产生引起的，与基础阻力和冰速的乘积成正比。冰流的宽度由缓慢移动的河间山脊的冰夹带或侵蚀与从山脊进入冰流的平流之间的平衡决定。脊冰的夹带被参数化为侧向边缘处的剪应力的函数，在一种情况下与侧向剪应力成正比，在第二种情况下与冰流宽度成比例。在第一个公式中，模型很快变得不稳定，但使用第二个公式，通过提供全部或大部分流动阻力的横向阻力达到稳定状态。结果表明理解夹带非常重要。对于第二个模型和广泛的参数值，不存在循环行为，快速流动之后是静止阶段。
A simple model is developed based on the notion that on active ice streams the resistance to flow is partitioned between basal drag and lateral drag. The relative roles of these sources of resistance is determined by a friction parameter that effectively describes the strength of the bed under the ice stream. Reduction in the basal strength is caused by meltwater production, taken proportional to the product of basal drag and ice speed. The width of the ice stream is governed by the balance between entrainment or erosion of ice from the slow-moving inter-stream ridges and advection from the ridges into the ice stream. Entrainment of ridge ice is parameterized as a function of the shear stress at the lateral margins, in one case proportional to the lateral shear stress and in the second case scaled to ice-stream width. In the first formulation, the model rapidly becomes unstable but, using the second formulation, a steady state is reached with lateral drag providing all or most of the resistance to flow. The results point to the great importance of achieving an understanding of entrainment. With the second model and a wide range of parameter values, there is no cyclic behavior, with rapid flow being followed by a quiescent phase.