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

汉密尔顿/1246400该奖项支持麦克默多剪切带（SZ）的综合实地观测，遥感和数值模拟研究。SZ是一个5-10 km宽的严重裂缝冰带，分隔了麦克默多和罗斯冰架，是罗斯冰架的重要横向支撑区域。以前的雷达和遥感研究揭示了一个谜的图片的SZ，在深度检测到的裂缝没有明显的表面表达，并有可能与所观察到的流场不一致的方向。在拟议的工作中，我们试图测试的假设，SZ是一个区域的混沌拉格朗日混合（相交）埋裂隙，导致流变不稳定，可能允许大规模的速度不连续性。这项工作将包括使用探地雷达对决口分布和结构进行详细的实地观测，以及对SZ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，雷达调查将主要在轻型机器人车辆的帮助下进行。观测结果将用于建立冰架剪切边缘行为的有限元模型。 该项目的智力价值是增加对冰架剪切边缘动力学的理解。剪切边缘在冰架稳定性中起着关键作用，而冰架反过来又调节了从冰盖穿过接地线到海洋的冰通量。该项目的见解将改进正在开发的大型模型，以预测冰盖演变和未来海平面上升的速度，这是社会关注的重大问题。 该项目更广泛的影响包括改善美国南极计划物流规划的基础，以及让K-12学生参与科学发现的众多机会。罗斯冰架和麦克默多冰架之间剪切带的裂缝加剧，将妨碍重型横移车辆穿越南极表面，这将导致向南极运送燃料的成本增加，并同时损失重型飞机在南极洲执行科学任务所需的飞行时间。我们的多学科研究结合了冰川学，数值建模和机器人工程，是一种引人入胜的方式来展示机器人如何帮助科学家收集危险的现场测量。我们的外展活动将利用达特茅斯目前的NSF GK-12计划，建立在缅因州大学最近的GK-12计划期间建立的教师-教育工作者关系，并将项目结果纳入缅因州的IDEAS倡议，该倡议将计算建模与中学现有的科学课程相结合。这个奖项在南极洲有实地工作。

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.