In search of ice-stream sticky spots
In search of ice-stream sticky spots
复制标题
寻找冰流粘点
作者：
R. Alley
摘要 冰流的基础剪切应力可能不成比例地受到局部区域或“粘性点”的支撑。粘在冰流底部的大基岩隆起物引起的阻力是产生粘点的最可能原因。润滑槽的不连续性可能会导致粘点，但它们会收集润滑水，因此不太可能支撑超过十分之几的剪切应力，除非它们包含大量的大凸块。冰-空气表面上的凸起区域也会导致下方床层支撑的剪切应力适度增加。对大范围河床粗糙度的调查将识别由基岩隆起引起的粘性点，在薄或零水碴区域的水压测量可能会揭示它们是否是粘性点，跨越冰面高点边缘的应变网格将显示高点是否引起粘性点。粘性点可能在控制西南极洲上游 B 营地附近的冰流 B 方面并不占主导地位。
Abstract The basal shear stress of an ice stream may be supported disproportionately on localized regions or “sticky spots”. The drag induced by large bedrock bumps sticking into the base of an ice stream is the most likely cause of sticky spots. Discontinuity of lubricating till can cause sticky spots, but they will collect lubricating water and therefore are unlikely to support a shear stress of more than a few tenths of a bar unless they contain abundant large bumps. Raised regions on the ice-air surface can also cause moderate increases in the shear stress supported on the bed beneath. Surveys of large-scale bed roughness would identify sticky spots caused by bedrock bumps, water-pressure measurements in regions of thin or zero till might reveal whether they were sticky spots, and strain grids across the margins of ice-surface highs would show whether the highs were causing sticky spots. Sticky spots probably are not dominant in controlling Ice Stream Β near the Upstream Β camp, West Antarctica.