Flow Laws For Glacier Ice: Comparison Of Numerical Predictions And Field Measurements
Flow Laws For Glacier Ice: Comparison Of Numerical Predictions And Field Measurements
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冰川冰的流动定律：数值预测与现场测量的比较
DOI：
10.3189/002214390793701372
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发表时间：
1990
影响因子：
3.4
通讯作者：
I. Whillans
中科院分区：
文献类型：
--
作者：
C. J. van der Veen;I. Whillans
摘要 详细研究了格陵兰岛 Dye 3 钻孔上游 20 公里长应变网络的冰流。通过求解力平衡方程并使用选定的流动定律，可以计算整个冰盖部分的应力和应变率。通过与钻孔倾斜测量得出的速度剖面以及观察到的表面应变率进行比较来评估结果的有效性。如果使用适当的增强因子，尝试了许多本构关系，并且大多数预测了钻孔位置处的速度剖面，该速度剖面与观察到的速度剖面非常一致。然而，模型和测量的表面应变率之间存在重大差异。使用格伦流动定律的奈推广，或各向异性本构关系，需要增强因子的不切实际的大的沿流变化。包含正应力效应可以得到更好的一致性，但极地冰的本构关系中可能还应包含其他过程，例如动态再结晶或初级蠕变。
Abstract Ice flow along the 20 km long strain network up-stream of the Dye 3 bore hole in Greenland is studied in detail. By solving the force-balance equations and using selected flow laws, stresses and strain-rates are calculated throughout the section of the ice sheet. The validity of the results is evaluated by comparison with the velocity profile derived from bore-hole-tilting measurements, and with observed surface strain-rates. A number of constitutive relations are tried and most predict a velocity profile at the bore-hole site that is in good agreement with that observed, if appropriate enhancement factors are used. However, there are major discrepancies between modelled and measured surface strain-rates. Use of Nye’s generalization of Glen’s flow law, or an anisotropic constitutive relation, requires unrealistically large along-flow variations in the enhancement factor. Inclusion of normal stress effects can lead to much better agreement, but it is possible that other processes, such as dynamic recrystallization or primary creep, should be included in the constitutive relation of polar ice.