STEADY THERMOMECHANICAL FLOW ALONG TWO-DIMENSIONAL FLOW LINES IN LARGE GROUNDED ICE SHEETS
STEADY THERMOMECHANICAL FLOW ALONG TWO-DIMENSIONAL FLOW LINES IN LARGE GROUNDED ICE SHEETS
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DOI：
10.1029/jb094ib08p10355
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发表时间：
1989-08-10
期刊：
影响因子：
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通讯作者：
DAHLJENSEN, D
中科院分区：
文献类型：
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作者：
DAHLJENSEN, D
为了同时计算大冰盖上二维流线上的表面高度、应力、速度和温度的分布，发展了一个热力学流动模型。为了求解完全热力耦合方程的复杂系统，进行了如下近似：给出前导降阶模型的坐标标度和将能量平衡方程与其余方程解耦的迭代过程。模型采用Glen流动定律作为应力与变形的本构关系，发现纵向偏应力在前序方程中起着重要的作用。在冰的分割处，解表明速度、应力和温度分布变化很快。在这里，基础温度上升，形成一个“热点”。表面应变率增加50%，水平速度分布在底部附近呈凹形，有拐点。远离冰区，基面温度升高，在这里的例子中，基面温度在侧向范围的2/3之后达到压力熔点，基面滑动开始影响流动。在消融区，内部变形产生的热量与来自基岩的地热通量具有相同的数量级。
A thermomechanical flow model has been developed in order to perform simultaneous calculations of the surface elevation and the distribution of stresses, velocities, and temperatures along two‐dimensional flow lines on large grounded ice sheets. In order to solve the complex system of full thermomechanical coupled equations the following approximations have been made: A coordinate scaling giving a lead order reduced model and an iteration procedure, which decouples the energy balance equation from the rest of the equations. Glen's flow law is used as the constitutive relationship between stresses and deformation in the model, and it is found that the longitudinal deviatoric stresses have a significant role in the lead order equations. At the ice divide the solution shows that the velocity, stress, and temperature distributions change rapidly. Here the basal temperature increases creating a “hot spot.” The surface strain rates increase 50% and the horizontal velocity profile is concave near the base, with an inflection point. Away from the ice divide, basal temperature increases, and in the example presented here the basal temperature reaches the pressure melting point after 2/3 of the lateral extent and basal sliding begins to influence the flow. In the ablation region it is seen that the heat produced by internal deformation is of the same order of magnitude as the geothermal heat flux from the bedrock.