Till beneath ice stream B: 4. A coupled ice-till flow model
Till beneath ice stream B: 4. A coupled ice-till flow model
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冰流 B 下方的耕地：4. 冰-耕地流耦合模型
DOI：
10.1029/jb092ib09p08931
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发表时间：
1987
影响因子：
--
通讯作者：
C. Bentley
中科院分区：
文献类型：
--
作者：
R. Alley;D. Blankenship;S. Rooney;C. Bentley
一个非定常模型的冰流流动的变形直到表明，系统响应迅速，并在一个稳定的方式合理的边际扰动。对于该模型，我们需要一维流动和连续的冰和冰碛，我们假设线性粘性直到流变和冰流的驱动应力和阻力之间的平衡在床上。这使我们能够写出冰厚和冰碛厚度随时间变化率的耦合方程，用这些厚度和冰碛粘度来表示。南极洲西部冰流B的一个解析稳态解表明，冰碛物的粘性在下游缓慢减小，这可能与下游有效压力的减小有关。非定常数值实验与固定的冰厚度在两端表明，一个边际扰动导致调整波旅行的冰流的长度在大约50年，一个新的稳定状态在大约200年。冰碛物厚度的变化倾向于缓和冰中的扰动，从而稳定系统。
A nonsteady model of an ice stream flowing on deforming till shows that the system responds rapidly and in a stable manner to reasonable marginal perturbations. For the model we require one-dimensional flow and continuity of ice and till, and we assume linear viscous till rheology and balance between the driving stress for ice flow and the resistive stress at the bed. This allows us to write coupled equations for the time rate of change of the ice thickness and the till thickness in terms of these thicknesses and the till viscosity. An analytic, steady state solution for ice stream B, West Antarctica, shows that till viscosity decreases slowly downstream, probably in response to decreasing effective pressure downstream. Nonsteady numerical experiments with fixed ice thicknesses at the ends show that a marginal perturbation causes a wave of adjustment to travel the length of the ice stream in about 50 years, with a new steady state in about 200 years. Changes in till thickness tend to moderate perturbations in the ice and thus stabilize the system.