The nature of complex ice flow in Shirase Glacier catchment, East Antarctica
The nature of complex ice flow in Shirase Glacier catchment, East Antarctica
复制标题
东南极洲白濑冰川流域复杂冰流的性质
作者：
F. Pattyn;R. Naruse
摘要研究了东南极洲Shirase冰川汇水下游地区内陆向复杂冰流的转变过程。在Shirase冰川接地线上游230公里处的250公里长的Mizuho三角测量链（MTC; Naruse, 1978），结合平衡速度估算，通过力平衡分析重新分析。数值模型实验采用二维热力学高阶冰盖模型，沿中央流线从冰分界线（Dome Fuji）延伸至Shirase冰川接地线，穿过MTC。结果表明：复合流动起源于MTC附近，其中纵向法向应力和法向阻力对力平衡起决定性作用；然而，快速流动区域受到地质控制，并被限制在接地线上游几十公里的“瓶颈”或冰流汇合区域。在MTC和接地带之间，纵向正应力和基底滑动是冰流状态的主要特征。
Abstract The transition of inland to complex ice flow is investigated in the downstream area of Shirase Glacier catchment, East Antarctica. The 250 km long Mizuho Triangulation Chain (MTC; Naruse, 1978), 230 km upstream of the grounding line of Shirase Glacier, is re-analyzed by a force-balance analysis, in combination with balance-velocity estimates. Numerical model experiments were carried out with a two-dimensional thermomechanical higher-order ice-sheet model along a central flowline extending from the ice divide (Dome Fuji) to the grounding line of Shirase Glacier, passing through the MTC. Results show that complex flow originates near the MTC, where longitudinal normal stresses and normal drag in particular play a decisive role in the force balance. The fast-flow area, however, is geologically controlled and confined to the “bottleneck” or ice-flow convergence area, a few tens of kilometres upstream of the grounding line. In between the MTC and the grounding zone, longitudinal normal stress and basal sliding are dominant features of the ice-flow regime.