A numerical model of interactions between a polar ice stream and the ocean: Application to ice stream E, West Antarctica
A numerical model of interactions between a polar ice stream and the ocean: Application to ice stream E, West Antarctica
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极地冰流与海洋相互作用的数值模型：应用于南极洲西部冰流 E
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发表时间：
1984
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影响因子：
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通讯作者：
C. Lingle
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作者：
C. Lingle
建立了一个随时间变化的数值模式，用以研究在海平面以下接地的极地冰流的动力学。该模型被应用于冰流E，两个最活跃的冰流排水罗斯海部门的西南极冰盖。从浮动的罗斯冰架需要举行的模型接地线在动态平衡的阻滞力，或背应力，被发现比较密切的阻滞力从现场数据映射由早期的调查。这意味着，如果冰流及其集水区近似处于质量平衡，则冰流E的接地线实际上接近于动力平衡，既不快速前进也不快速后退。敏感性试验表明，模型冰流是更敏感的背应力从冰架的变化比在积累率的变化。背应力的变化可以由冰架平均厚度的变化引起。该模型被用来模拟后退的冰流从罗斯海大陆架的边缘在全新世期间的海平面上升。假定海底是均衡下沉的，但在后退期间保持刚性。通过考虑几种不同的冰架历史，研究了假定的罗斯冰架后退历史对计算的接地线后退时间的影响。这些结果支持了早期研究人员的结论，即罗斯冰架导致接地线在全新世大范围后退后，在其目前位置附近停止后退。此外，罗斯冰架的崩解锋的撤退时间对冰流接地线的撤退时间产生了重大影响。
A time-dependent numerical model has been developed to study the dynamics of a polar ice stream grounded below sea level. The model was applied to ice stream E, one of the two most active ice streams draining the Ross Sea sector of the West Antarctic ice sheet. The retarding force, or back stress, from the floating Ross Ice Shelf needed to hold the model grounding line in dynamic equilibrium was found to compare closely with retarding force mapped from field data by earlier investigators. This implies that the grounding line of ice stream E is in fact close to dynamic equilibrium, neither advancing nor retreating rapidly, if the ice stream and its catchment area are approximately in mass balance. Sensitivity tests showed that the model ice stream is more sensitive to changes in back stress from the ice shelf than to changes in the accumulation rate. Changes in back stress can be caused by changes in the average thickness of the ice shelf. The model was used to simulate retreat of the ice stream from the edge of the continental shelf in the Ross Sea during the Holocene period of rising sea level. The sea-floor was assumed to be isostatically depressed but to remain rigid during retreat. The effect of the assumed retreat history of the Ross Ice Shelf on the computed timing of grounding-line retreat was investigated by considering several alternative ice shelf histories. The results support the conclusion of earlier investigators that the Ross Ice Shelf caused the grounding line to stop retreating near its present position, after extensive retreat during the Holocene. In addition, the timing of retreat of the calving front of the Ross Ice Shelf exerted major influence on the timing of retreat of the ice stream grounding line.