A slip law for glaciers on deformable beds
A slip law for glaciers on deformable beds
复制标题
可变形床上冰川的滑移定律
作者：
L. Zoet;N. Iverson
冰川是如何流过它们下面的地面的？我们知道摩擦力、冰流速度和冰床上的水压都很重要，但我们仍然不知道如何表示硬床（固体岩石）和软床（由称为冰碛的未固结侵蚀产物组成）的过程。Zoet和Iverson展示了实验结果，描述了冰川冰如何在水饱和的冰碛上移动（参见Minchew和Joughin的观点）。这些意见应有助于解决长期存在的问题，建立一个广义的滑动定律，结合硬层滑动和床变形的过程。科学》，本期第76页;另见第29页实验揭示了冰川在软床上的滑动如何取决于速度。海洋终止冰流在可变形冰碛床上的滑动是西南极冰盖对海平面上升的主要贡献。其他地方的冰盖和冰床冰川的流动模型需要一个与滑动阻力、滑动速度和河床水压有关的定律。我们目前的实验结果，其中加压冰在其融化温度是滑过水饱和，直到床。稳态滑动阻力增加与滑动速度由于冰的滑动横跨床，但高于阈值速度，直到剪切在其速率无关的库仑强度。这些结果激发了冰川流模型，结合硬层滑动和河床变形过程的广义滑动法。
Slipping on till How do glaciers flow over the ground underlying them? We know that friction, ice stream velocity, and water pressure at the ice bed all matter, but we still do not know how to represent the process over both hard beds (which are solid rock) and soft ones (composed of unconsolidated erosion products called till). Zoet and Iverson present experimental results describing how glacial ice moves over watersaturated till (see the Perspective by Minchew and Joughin). These observations should help to solve the long-standing problem of constructing a generalized slip law that combines the processes of hard-bedded sliding and bed deformation. Science, this issue p. 76; see also p. 29 Experiments reveal how glacial slip over soft beds depends on velocity. Slip of marine-terminating ice streams over beds of deformable till is responsible for most of the contribution of the West Antarctic Ice Sheet to sea level rise. Flow models of the ice sheet and till-bedded glaciers elsewhere require a law that relates slip resistance, slip velocity, and water pressure at the bed. We present results of experiments in which pressurized ice at its melting temperature is slid over a water-saturated till bed. Steady-state slip resistance increases with slip velocity owing to sliding of ice across the bed, but above a threshold velocity, till shears at its rate-independent Coulomb strength. These results motivate a generalized slip law for glacier-flow models that combines processes of hard-bedded sliding and bed deformation.