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

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 project 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 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.