Stress Transmission at Ice-Stream Shear Margins

这一奖项是为了支持一项为期三年的计划，该计划旨在研究三个冰流剪切边缘的应力传递。其目的是确定冰流的运动在多大程度上受控于流间脊，将这种横向阻力的大小与冰流上的驱动应力和冰流宽度进行比较，并确定横向阻力支持是否与边缘的横向迁移有关。通过应变率的测量，推导出在脊冰和冰流冰之间传递的单位冰流长度的净力。实地工作将需要安装偏远的水獭营地，每个营地在第一季期间将被占用约12天，在第二季期间将被占用约6天。南极洲航空地球物理研究支助办公室(SOAR)设施将进行航空测量，以确定溪间海脊上的冰厚度，以及冰流上的冰厚度和表面坡度。现场测量将得到邻近现场的冰流E的重复SPOT图像的补充，以便能够确定边缘冰流一侧的速度。将这些速度与应变网格调查获得的速度进行比较，将提供边缘冰层软化量的估计。

This award is for support for a three year program to study stress transmission at three ice stream shear margins. The objectives are to determine how much of the motion of the ice streams is controlled from the inter-stream ridges, to compare the magnitude of this lateral drag with the driving stress on the ice stream, and with ice stream width and to determine whether lateral drag support is associated with lateral migration of the margin. The net force per unit ice-stream length transmitted between ridge ice and ice-stream ice will be deduced from measurements of strain rate. Field work will entail Twin Otter installation of remote camps that will each be occupied for about 12 days during the first season and about 6 days during the second. The Support Office for Aerogeophysical Research in Antarctica (SOAR) facility will conduct aerial surveys to determine ice thickness on the inter-stream ridges, as well as the ice thickness and surface slope on the ice streams. The field measurements will be complemented by repeat SPOT imagery of Ice Stream E adjacent to the field site, to allow velocities in the ice-stream side of the margin to be determined. Comparing these velocities to those obtained from the strain-grid surveys will provide an estimate of the amount of softening of the ice in the margins.