Researchers report field observations of the rapid draining of a lake on the Greenland Ice Sheet. Supraglacial lakes can drain to the bed of ice sheets in a matter of hours, altering ice dynamics on multiple timescales. Previously, field observations of such rapid drainage on the Greenland Ice Sheet were conducted in slow-flowing, land-terminating areas. Thomas Chudley and colleagues used in-situ instrumentation and custom-built drones to measure lake volume and discharge, ice flow and uplift, and seismic activity during drainage of a lake on a fast-flowing, marine-terminating glacier in West Greenland in July 2018. Ice uplift and ice flow acceleration were greatest approximately 4 km downstream from the lake. Such large distal responses to drainage have not been previously observed. In contrast to previous studies where lakes drained completely, only two-thirds of the lake volume drained. Such partial drainage events had previously been assumed to occur slowly over days, but, in this instance, the authors report, nearly 5 million cubic meters drained in less than 5 hours. The results suggest that even partial drainage events rapidly deliver water to the bed. Hence, the number and impact of rapid drainage events may have been underestimated, according to the authors.
Article #19-13685: "Supraglacial lake drainage at a fast-flowing Greenlandic outlet glacier," by Thomas R. Chudley et al.
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