Collaborative Research: The Greenland Firn Aquifer Impacts on Ice Sheet Hydrology: Characterizing Volume, Flow, and Discharge

这个项目将继续进行最近的偶然发现，即在格陵兰岛南部冰盖的坚硬层内全年都存在液态水。这一发现揭示了融水的另一条途径，使人们对冰盖表面融化与海平面上升之间关系的理解变得更加复杂。即使是关于地下含水层的最基本的问题也没有答案。该提案将解决三个基本的研究问题：1。firn含水层与更广泛的格陵兰水文系统的途径和联系是什么？含水层对海平面上升的影响是什么？在格陵兰岛firn含水层中储存的液态水的质量/体积是多少？含水层中水流的速率和模式是什么？这些问题将通过标准地下水采样技术、地震探测、核磁共振和冰芯测量来解决。这项研究将在两个末端成员假设的指导下推进对格陵兰firn含水层的认识，这些假设提出了这些储存的水离开含水层的可能途径。含水层与发育良好的冰川水文网络相连，包括裂缝和冰碛，它们以相对恒定的速率（季节性）将含水层的一部分排到河床上，类似于格陵兰岛西部的地表融化。或2：含水层主要将水储存在可用的坚硬孔隙空间中，在孔隙空间完全饱和和/或达到导致释放事件的阈值之前不会释放水。很可能每一种机制的某些部分都与冰盖上的位置有关。拟议的实地研究以及局部和区域模拟研究的重点是沿着进入Helheim冰川的冰流线的高程梯度，旨在确定每个路径的相对贡献。这些知识是准确测量和预测格陵兰冰盖所必需的吗？对海平面上升的现在和未来的贡献。此外，该研究还验证了测量冰川水量和流量的地面水文和地震技术，为未来的研究提供了新的多学科技术。更广泛的影响包括1)进一步了解格陵兰冰盖中以前未知的水储存；2)培养2名博士后，研究方向为冰川学和冰川建模；3)涉及研究生和本科生的；4)通过在格陵兰岛库鲁苏克学校的演讲来告知当地社区；5)通过既定的外展项目向广大公众宣传。

This project will follow up on the serendipitous recent discovery that liquid water is present year-round within the firn layer of the southern Greenland Ice Sheet. This discovery complicates understanding of the relationship of surface melting on the ice sheet to sea level rise by revealing another pathway for meltwater to take. Even the most fundamental questions about the firn aquifer remain unanswered. This proposal will address three essential research questions: 1. What are the pathways and connections of the firn aquifer with the broader Greenland hydrologic system and what is the aquifer's effect on sea level rise?2. What is the mass/volume of the liquid water stored in the Greenland firn aquifer?3. What are the rates and patterns of water flow in the aquifer?These questions will be addressed using standard groundwater sampling techniques, seismic sounding, nuclear magnetic resonance, and ice core measurements.This research will advance knowledge of the Greenland firn aquifer guided by two end member hypotheses that present possible pathways for this stored water to exit the aquifer. 1: The aquifer is connected to a well-developed englacial hydrologic network, including crevasses and moulins, that drain some portion of the aquifer at a relatively constant rate (seasonally) to the bed, similar to surface melt in western Greenland. or 2: The aquifer is primarily storing water in available firn pore space and will not release water until the pore space is completely saturated and/or a threshold is met leading to a release event. It is likely that some proportion of each mechanism is relevant depending upon location on the ice sheet. The proposed field studies along with local and regional modeling studies focused along an elevation gradient of an ice flow line into Helheim Glacier are aimed at determining the relative contribution of each pathway. This knowledge is required to accurately measure and predict the Greenland ice sheet?s present and future contribution to sea level rise. Additionally this research verifies ground hydrology and seismic techniques for measuring englacial water volume and flow providing new multi-disciplinary techniques for future research. Broader impacts include 1) gaining further understanding of a previously unknown storage of water in the Greenland Ice Sheet; 2) training two postdoctoral researchers, in glaciology and firn modeling; 3) involving graduate and undergraduate students; 4) Informing the local community by presenting at the Kulusuk, Greenland School; 5) Informing the broad public through established outreach programs.