C058-02
Greenland supraglacial discharge measurements highly correlated with diurnal ice sheet motion

Tuesday, 15 December 2020: 11:34
Virtual
Laurence C Smith1, Lauren C Andrews2, Lincoln H H Pitcher3,4, Brandon T Overstreet5, Asa K Rennermalm6, Matthew G G Cooper7, Sarah W Cooley8, Johnny Ryan1, Clément Miège9, Charles Mark Kershner10 and Claire E Simpson11, (1)Brown University, Providence, RI, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)University of California Los Angeles, Los Angeles, CA, United States, (4)CIRES, Boulder, CO, United States, (5)University of Wyoming, Laramie, WY, United States, (6)Rutgers University, New Brunswick, NJ, United States, (7)University of California, Los Angeles, Geography, Los Angeles, CA, United States, (8)Stanford University, Stanford, CA, United States, (9)University of Utah, Salt Lake City, UT, United States, (10)George Mason University Fairfax, Fairfax, VA, United States, (11)RedCastle Resources, onsite contractor to USDA Forest Service, Geospatial Technology and Applications Center (GTAC), Salt Lake City, UT, United States
Recorded Presentation
Abstract:
Meltwater runoff generated on the Greenland Ice Sheet surface enhances seasonal ice motion by supplying water to the bed, but physical processes coupling supraglacial runoff with subglacial processes remain poorly understood. We present 174 hourly in situ Acoustic Doppler Current Profiler (ADCP) measurements of supraglacial runoff entering the terminal moulin of Rio Behar, a 63 km2 mid-elevation (~1200 m a.s.l.) internally drained catchment on the southwest Greenland ablation zone. Comparison of these hourly discharges with simultaneously acquired GPS estimates of local ice surface uplift rate, ice surface speed, and measures of surface mass loss reveal a high correlation of supraglacial discharge with diurnal ice speed variations. A proxy for subglacial water storage rate-of-change, determined by comparing normalized supraglacial and proglacial discharge hydrographs, aligns with diurnal variations in ice speed. We conclude that moulin-driven fluctuations in diurnal subglacial water storage, rather than absolute subglacial water storage, drive diurnal ice speed variations near Rio Behar moulin despite its moderate ice thickness (nearly 1 km) and >40 km distance from the ice edge.
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