Collaborative Research: In Situ Borehole Measurements To Partition The Velocity Of The Greenland Ice Sheet Into Ice Deformation And Basal Sliding Components

合作研究：现场钻孔测量将格陵兰冰盖的速度划分为冰变形和基底滑动分量

• 批准号: 1203418
• 负责人: Joel Harper
• 金额: $ 58.96万
• 依托单位: University of Montana
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-10-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1203418&HistoricalAwards=false
• 关键词: Collaborative; Research; Situ; Borehole; Measurements

Sliding of an ice mass along its basal boundary is a fundamental component of motion where bed conditions are wet. Estimates of basal sliding generally result from an inverse analysis of observed surface motion using a model assuming Glen?s generalized constitutive law for isotropic ice. Evidence suggests that this law does not adequately represent ice deformation, due to a variety of issues including ice thermal variations, preferred fabric, and chemical impurities in the ice. The PIs propose an innovative experimental design to improve our understanding of the ice deformation and sliding. A grid of 9 boreholes, each approximately 750 m in depth and extending to the bed, will be drilled through the Greenland Ice Sheet and instrumented with more than 675 sensors to observe ice temperature, ice deformation, and basal sliding. Analysis of the resulting data set will yield the full 3D velocity field and full stress and strain rate tensors for a 420x106 m3 block of ice. The results will be used to assess and improve the constitutive law and will provide a data set for testing inversion methodologies.The Greenland and Antarctic Ice Sheets contain enough water to cause massive inundation of heavily populated coastal regions and associated infrastructure, if they were to degrade significantly through melting or delivery of icebergs to the coastal ocean. Our ability to predict future sea level rise is hampered by an inability to accurately model glacier dynamics that connect these ice sheets to the ocean. This project will provide data sets and consequent insight into processes that will lead to improved models of glacier dynamics.

冰块沿着基础边界的滑动是床条件湿的运动的基本组成部分。 基础滑动的估计值通常是由于观察到的表面运动的反向分析，该模型假设Glen是各向同性冰的广义构成定律。 有证据表明，由于包括冰热变化，首选织物和冰中的化学杂质在内的各种问题，该定律不能充分代表冰变形。 PI提出了一种创新的实验设计，以提高我们对冰变形和滑动的理解。 将通过格陵兰冰盖钻出9个钻孔的网格，每个孔的深度约为750 m，并延伸至床，并用超过675个传感器进行仪器，以观察冰温，冰变形和基础滑动。 对所得数据集的分析将产生完整的3D速度场以及420x106 M3冰块的完全应力和应变率张量。 该结果将用于评估和改善本构法律，并将提供用于测试反转方法的数据集。格陵兰和南极冰盖含足够的水，以引起人口稠密的沿海地区及相关基础设施的大量淹没，如果它们通过向冰山融化或交付冰山而显着降低了这些水。 我们无法准确地对将这些冰盖与海洋联系起来的冰川动力学对未来海平面上升的能力受到阻碍。 该项目将提供数据集，并因此深入了解过程，从而改善冰川动态模型。