Greenland Ice Sheet dynamic response to inland expansion of a hydrologically-active ice-sheet bed

格陵兰冰盖对水文活跃冰盖床内陆扩张的动态响应

• 批准号: 2003464
• 负责人: Meredith Nettles
• 金额: $ 72.26万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003464&HistoricalAwards=false
• 关键词: Greenland; Ice; Sheet; dynamic; response

The Greenland Ice Sheet’s contribution to sea-level rise is accelerating, partly due to the acceleration of ice-sheet flow. Melt from the ice-sheet surface can reach the base of the ice and change ice flow, but this effect is complex and poorly understood. As the climate warms and the area of the ice surface undergoing surface melting expands inland, important questions include whether a larger area of the ice-sheet bed will receive injections of meltwater, and whether this will lead to faster flow. This 3-year project will make measurements of ice-sheet velocity and deformation along a transect of supraglacial lakes and moulins, which provide surface-to-bed meltwater pathways, on the Greenland Ice Sheet. These on-ice measurements will allow improved understanding of the processes controlling water access to the ice-sheet bed in regions of new supraglacial lake formation, with a focus on the process of hydro-fracture (water-driven fracture). The project will support an educational partnership between Lamont-Doherty Earth Observatory scientists and the New York City Department of Education to develop and implement a series of classroom sessions focused on geophysics applied to the Greenland Ice Sheet and New York City environments. This project will train one graduate student and support a postdoctoral scientist and an early career scientist.The current inland migration of surface melt is unprecedented in the observational era. A fundamental challenge in predicting the ice sheet’s dynamic flow response to the injection of surface meltwater at the ice-sheet bed is quantifying stresses in areas of nascent supraglacial lake formation in the mid- to upper-ablation zone of the ice sheet. In this project, Global Positioning System (GPS) and autonomous phase-sensitive radar units will be deployed over a 16-month period to measure ice-sheet surface velocity, surface and englacial strain, and stress transients around supraglacial lakes and moulins in the mid- to upper-ablation zone. These field data will be used in conjunction with geophysical inverse modeling techniques to compute surface and englacial stress and deformation patterns and to quantify the processes controlling water access to the ice-sheet bed. A major goal of the research is to address fundamental questions that will move us towards being able to describe the dynamic impact of surface-to-bed meltwater transit in prognostic ice-sheet models for both the Greenland Ice Sheet and Antarctic Ice Sheet. Quantifying the stresses necessary to initiate hydro-fracture or moulin formation over a range of ice thicknesses and viscous strain rates allows for the extension of these findings to thousands of existing and forthcoming lakes on grounded regions of these ice sheets. Moreover, combining observations of englacial strain and surface deformation has the potential to transform our understanding of ice-sheet deformation, by allowing an empirical test of the assumption that an elastic model is appropriate for inverting observations of surface deformation of glacial ice on short timescales. Answering the question of whether, and when, the Greenland Ice Sheet interior will respond dynamically to surface melt is vital for predicting sea-level rise. The engagement of school students and doctoral and postdoctoral trainees will broaden participation in the Earth Sciences and help train the next generation of interdisciplinary geoscientists.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.

格陵兰冰层的上升正在加速，部分是由于ACE流量可以到达冰的底部，并改变冰的冰流，但是这种效果是复杂的，并且对冰盖床的理解很差。接收融化年度项目的注射将测量沿冰片速度和变形，沿着冰川上湖上的湖泊湖湖电子到床的融合水路，在格陵兰冰盖上可以提高对控制过程的理解。在新的上冰湖造型地区，该项目将支持Lamont-Doherty Earth Observitive科学家与新的新型新的新新的新型新新的新新新新新新纽约之间的教育合作伙伴城市部门开发和实施一系列专注于Greenland Iceet和New York City环境的地球物理学的课程冰层床的表面融化量量化了该项目的冰盖中部到上层区域的区域上乳流湖中的应力。 AO6的月段以测量冰片表面速度，表面和英式应变，以及在上层区域中的冰川上湖周围的应力瞬变。压力和变形模式，并量化了对冰床的水的访问，用于预后的冰层模型。在一系列冰的范围内形成了这些冰块的数千个thorthcomcy湖的延伸。时间尺度。当对表面熔体的响应的格陵兰冰板对于预测海平面上升的效果是至关重要的。值得使用Tountellectul的功绩和Roader影响审查标准的支持Therugh评估。