A modified theory of bottom crevasses used as a means for measuring the buttressing effect of ice shelves on inland ice sheets
A modified theory of bottom crevasses used as a means for measuring the buttressing effect of ice shelves on inland ice sheets
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修正的底部裂缝理论用作测量冰架对内陆冰盖的支撑效应的方法
DOI：
10.1029/jb089ib03p01925
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发表时间：
1984
影响因子：
--
通讯作者：
K. Jezek
中科院分区：
文献类型：
--
作者：
K. Jezek
底部裂缝是向上延伸到浮动冰架的裂缝。当海水渗透到冰架底部并使冰破裂到冰内应力等于海水应力的水平时，它们就形成了。对于一个自由浮动的冰架，密集冰隙的穿透高度估计约为冰厚h的一半;对于一个孤立的冰隙，穿透高度约为πh/4。然而，对罗斯冰架底部裂缝的高度和位置的分析表明，没有一个裂缝接近预测的极限，这可能是因为现有的理论不包括有界冰架中存在的背应力σB。通过将理论重新表述为包括背应力项，可以根据雷达测量的裂缝高度和冰厚来实验评估σB。σB的大小（冰架西北角网格中的2个小节）表明冰架在支撑内陆冰盖方面发挥着重要作用。
Bottom crevasses are fractures that extend upward into floating ice shelves. They form when seawater penetrates the base of the ice shelf and ruptures the ice up to the level at which englacial stresses equal the stress of the seawater. For a freely floating ice shelf, the penetrating level of closely spaced crevasses is estimated at about half the ice thickness h; for an isolated crevasse the level is about πh/4. However, an analysis of the heights and locations of bottom crevasses in the Ross Ice Shelf shows that none of the crevasses approach the predicted limits, perhaps because the existing theory does not include the back stress σb which is present in bounded ice shelves. By reformulating the theory to include a back stress term, σb can be evaluated experimentally from radar measurements of crevasse height and ice thickness. The magnitude of σb (2 bars in the grid northwest corner of the ice shelf) suggests the ice shelf is playing an important role in buttressing the inland ice sheet.