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

该项目将跟进最近偶然发现的一项新发现，即格陵兰南部冰盖的冰层中常年存在液态水。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的关系的理解变得更加复杂。即使是关于积雪含水层的最基本的问题也没有得到回答。这项建议将解决三个基本的研究问题：1.冰雪含水层与更广泛的格陵兰水文系统有什么路径和联系，以及含水层对海平面上升的影响是什么？2.格陵兰冰雪含水层中储存的液态水的质量/体积是多少？3.含水层中的水流速度和模式是什么？这些问题将使用标准的地下水采样技术、地震测深、核磁共振和冰芯测量来解决。这项研究将增进对格陵兰冰雪含水层的了解，这项研究将由两个最终成员假设指导，这些假设提出了这些储存的水离开含水层的可能路径。1：含水层与一个发达的冰川水文网络相连，包括裂缝和丘陵，它们以相对恒定的速度(季节性地)将含水层的某些部分排到床上，类似于格陵兰西部的地表融化。或2：含水层主要将水储存在可用的孔隙空间中，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。根据冰盖上的位置，每种机制中可能有一定比例是相关的。拟议的实地研究以及当地和区域模拟研究的重点是沿进入海尔海姆冰川的冰流线的海拔梯度，目的是确定每条路径的相对贡献。这些知识是准确测量和预测格陵兰冰盖所必需的？S现在和未来对海平面上升的贡献。此外，这项研究还验证了用于测量冰川水量和流量的地面水文学和地震技术，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量；2)培训两名博士后研究人员，学习冰川学和冰雪模型；3)涉及研究生和本科生；4)通过在格陵兰Kulusuk学校演讲向当地社区提供信息；5)通过既定的外联计划向广大公众提供信息。

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.