Science / project summary
Much of the snow that covers the Greenland Ice Sheet experiences melting during summer months. This meltwater percolates and refreezes within the underlying snow. Over time, this altered snow, which is referred to as firn, can reach to depths of 100 meters. These changes in firn structure consequently alter the heat flow within the ice, and between the ice sheet and the atmosphere. As yet however, the full structure of the firn layer is unclear as observations have been limited to shallow depths. To address this important lack of understanding, the investigators will plan a field study focused on drilling a number of deep ice cores, with the goal of characterizing the thermal and physical properties of the deep firn ice. This information is essential to predicting ice sheet changes in volume and sea level rise. The project involves graduate and undergraduate students, an early career scientist, and includes public outreach activities. The project will test the hypothesis that the deep firn in the low elevation regions of Greenland experience densification governed by water infiltration/refreezing and thermally enhanced compaction. The project will develop a novel hot water drilling system to quickly penetrate 100 meters through the technically challenging conditions of intermixed cold and wet firn. In situ data collection will include digital temperature strings, video and core logging, and an instrumented drill stem. This work will yield a full-depth characterization of firn thickness, density, permeability, and thermal status. Moreover, drilling conducted a decade earlier in the region will permit the investigators to assess changes in firn properties over time. Ultimately, understanding meltwater retention and refreezing processes across Greenland’s accumulation area is essential for advancing prediction of ice sheet volume change, flow dynamics, and sea level change. The project will provide field and laboratory research experiences impacting a large number of undergraduate and graduate students. The project will support a newly funded young investigator, and will include outreach activities targeting the general public and middle school students in Greenland and Western Montana.