Basal friction of Ice Stream E, West Antarctica
Basal friction of Ice Stream E, West Antarctica
复制标题
南极洲西部冰流 E 的底部摩擦力
作者：
D. Macayeal;R. Bindschadler;T. Scambos
摘要我们使用来自连续的陆地卫星图像的表面速度和控制方法来估计一个主要的西南极冰流的底部摩擦分布。区域平均基底应力约为1.4 × 104Pa，约为区域平均驱动应力4.9 × 104Pa的29%。导出的面积平均基底应力的不确定性是难以评估的，主要取决于本构关系中的流动律速率因子的空间变化。与深度平均温度变化相关的空间变化给出了约±103 Pa的不确定性。大约60%的冰流具有小于104 Pa的基底应力大小，并且大约30%具有小于103 Pa的基底应力大小。这些特征表明存在一个机械薄弱，水充电冰下冰碛。小规模的粘性点，其中基础摩擦超过面积平均驱动应力不规则地分散在整个冰下制度，包括约15%的冰流面积。在陆地卫星图像显示下伏基岩具有结构特征的地区，粘点聚集在一起。
Abstract We use surface velocity derived from sequential Landsat imagery and a control method to estimate the basal-friction distribution of a major West Antarctic ice stream. The area-averaged basal stress is approximately 1.4 × 104 Pa, or about 29% of the area-averaged driving stress of 4.9 × 104 Pa. Uncertainty of the derived area-averaged basal stress is difficult to assess and depends primarily on spatial variation of the flow-law rate factor in the constitutive law. Spatial variation associated with depth-averaged temperature variation gives an uncertainty of approximately ±103 Pa. Approximately 60% of the ice stream has a basal-stress magnitude less than 104 Pa, and approximately 30% has less than 103 Pa. These characteristics suggest the presence of a mechanically weak, water-charged subglacial till. Small-scale sticky spots where basal friction exceeds the area-averaged driving stress are scattered irregularly across the subglacial regime and comprise approximately 15% of the ice-stream area. Sticky spots cluster in regions where Landsat imagery suggests structural features in the underlying bedrock.