Collaborative Research: Flow and Fracture Dynamics in an Ice Shelf Lateral Margin: Observations and Modeling of the McMurdo Shear Zone

合作研究：冰架侧缘的流动和断裂动力学：麦克默多剪切带的观测和建模

• 批准号: 1245915
• 负责人: Laura Ray
• 金额: $ 42.5万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1245915&HistoricalAwards=false
• 关键词: Collaborative; Research; Flow; Fracture; Dynamics

Hamilton/1246400This award supports an integrated field observation, remote sensing and numerical modeling study of the McMurdo Shear Zone (SZ). The SZ is a 5-10 km wide strip of heavily crevassed ice that separates the McMurdo and Ross ice shelves, and is an important region of lateral support for the Ross Ice Shelf. Previous radar and remote sensing studies reveal an enigmatic picture of the SZ in which crevasses detected at depth have no apparent surface expression, and have orientations which are possibly inconsistent with the observed flow field. In the proposed work, we seek to test the hypothesis that the SZ is a zone of chaotic Lagrangian mixing with (intersecting) buried crevasses which leads to rheological instability, potentially allowing large scale velocity discontinuities. The work will involve detailed field-based observations of crevasse distributions and structure using ground-penetrating radar, and GPS and remote sensing observations of the flow and stress field in the SZ. Because of the hazardous nature of the SZ, the radar surveys will be conducted largely with the aid of a lightweight robotic vehicle. Observations will be used to develop a finite element model of ice shelf shear margin behavior. The intellectual merit of this project is an increased understanding of ice shelf shear margin dynamics. Shear margins play a key role in ice shelf stability, and ice shelves in turn modulate the flux of ice from the ice sheet across the grounding line to the ocean. Insights from this project will improve large-scale models being developed to predict ice sheet evolution and future rates of sea level rise, which are topics of enormous societal concern. The broader impacts of the project include an improved basis for US Antarctic Program logistics planning as well as numerous opportunities to engage K-12 students in scientific discovery. Intensified crevassing in the shear zone between the Ross and McMurdo ice shelves would preclude surface crossing by heavy traverse vehicles which would lead to increased costs of delivering fuel to South Pole and a concomitant loss of flight time provided by heavy-lift aircraft for science missions on the continent. Our multidisciplinary research combining glaciology, numerical modeling, and robotics engineering is an engaging way to show how robotics can assist scientists in collecting hazardous field measurements. Our outreach activities will leverage Dartmouth's current NSF GK-12 program, build on faculty-educator relationships established during University of Maine's recent GK-12 program, and incorporate project results into University of Maine's IDEAS initiative, which integrates computational modeling with the existing science curriculum at the middle school level. This award has field work in Antarctica.

HAMILTON/1246400该奖项支持麦克默多剪切带(SZ)的综合野外观测、遥感和数值模拟研究。SZ是分隔麦克默多冰架和罗斯冰架的5-10公里宽的裂缝严重的冰带，也是罗斯冰架的重要横向支撑区。以前的雷达和遥感研究揭示了SZ的一幅神秘图景，其中在深处探测到的裂缝没有明显的表面表现，其方向可能与观测到的流场不一致。在拟议的工作中，我们试图检验这样的假设，即SZ是一个混杂着(相交的)埋藏裂缝的拉格朗日混沌区域，这导致了流变不稳定性，潜在地允许大规模的速度不连续。这项工作将包括使用探地雷达对裂缝分布和结构进行详细的现场观测，以及对深圳地区的流动和应力场进行全球定位系统和遥感观测。由于SZ的危险性质，雷达调查将主要在一辆轻型机器人车辆的帮助下进行。观测结果将被用来开发冰架剪切边缘行为的有限元模型。这个项目的学术价值在于增加了对冰架剪切边缘动力学的理解。剪切边缘对冰架的稳定性起着关键作用，而冰架反过来又调节着从冰盖穿过接地线进入海洋的冰通量。来自该项目的见解将改进正在开发的预测冰盖演变和未来海平面上升速度的大规模模型，这些都是巨大的社会关切的话题。该项目的更广泛影响包括改善了美国南极计划后勤规划的基础，以及许多让K-12学生参与科学发现的机会。罗斯冰架和麦克默多冰架之间剪切带的裂隙加剧，将阻止重型穿越车辆穿越冰面，这将导致向南极运送燃料的成本增加，并伴随着重型飞机为在大陆执行科学任务提供的飞行时间的损失。我们的多学科研究结合了冰川学、数值模拟和机器人工程，是展示机器人如何帮助科学家收集危险现场测量的一种引人入胜的方式。我们的外展活动将利用达特茅斯大学目前的NSF GK-12计划，建立在缅因州大学最近的GK-12计划期间建立的教职员工与教育工作者的关系，并将项目成果纳入缅因州大学的IDEAS计划，该计划将计算建模与现有的中学科学课程相结合。这一奖项在南极洲进行了实地考察。