RAPID Proposal: Constraining kinematics of the Whillans/Mercer Ice Stream Confluence

快速提案：Whillans/Mercer 冰流交汇处的约束运动学

• 批准号: 1842021
• 负责人: Seth Campbell
• 金额: $ 4.84万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1842021&HistoricalAwards=false
• 关键词: RAPID; Proposal; Constraining; kinematics; Whillans

The Siple Coast in West Antarctica has undergone significant glacier changes over the last millenium. Several ice streams--rapidly moving streams of ice bordered by slow-moving ice--exist in this region that feeds into the Ross Ice Shelf. A long-term slowdown of Whillans Ice Stream appears to be occurring, and this is affecting the zone between the Whillans and Mercer Ice Streams. However, the consistency of this slowdown and resulting changes to the shear margin between the two ice streams are unknown. The goal of this project is to quantify the observed changes over the past decade and understand the dynamic processes that cause them. A collateral benefit of and driver for this as a RAPID project is to test a method for assessing where crevassing will develop in this zone of steep velocity gradients. Such a method may benefit not only near-term field-project planning in the 2018-19 field season, but also planning for future fieldwork and traverses.The team will use remote sensing feature-tracking techniques to determine transient velocity patterns and shifts in the shear-zone location over the last 10-plus years. This velocity time series will be incorporated into a large-scale ice-sheet model to estimate ice-sheet susceptibility to changing boundary conditions over the next century based on likely regional ice-flux scenarios. This approach is an extension of recent work conducted by the team that shows promise for predicting areas of changing high strain rates indicative of an active glacier shear margin. The ultimate objectives are to characterize the flow field of merging ice streams over time and investigate lateral boundary migration. This will provide a better understanding of shear-margin control on ice-shelf and up-glacier stability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

西南极洲的西普尔海岸在过去的一千年里经历了重大的冰川变化。几个冰流--快速移动的冰流与缓慢移动的冰接壤--存在于这个区域，流入罗斯冰架。 惠兰斯冰流的长期减缓似乎正在发生，这正在影响惠兰斯和美世冰流之间的区域。然而，这种减速的一致性以及由此导致的两条冰流之间剪切边缘的变化是未知的。该项目的目标是量化过去十年中观察到的变化，并了解导致这些变化的动态过程。作为RAPID项目的一个附带好处和驱动因素，是测试一种方法，用于评估在该陡峭速度梯度区域中裂缝将在何处形成。 这种方法不仅有利于2018- 2019年野外季节的近期野外项目规划，也有利于未来的野外工作和穿越规划。该团队将使用遥感特征跟踪技术来确定过去10多年来剪切带位置的瞬时速度模式和变化。这一速度时间序列将被纳入一个大规模冰盖模型，以根据可能的区域冰通量情景估计冰盖对下一个世纪边界条件变化的敏感性。这种方法是该团队最近开展的工作的延伸，该工作显示出预测变化的高应变率区域的希望，这表明存在活跃的冰川剪切边缘。最终目标是表征合并冰流随时间的流场，并调查横向边界迁移。 这将使人们更好地了解冰架和冰川稳定性的剪切裕度控制。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。