Supraglacial lake drainage at a fast-flowing Greenlandic outlet glacier. ...

• Main Authors: Chudley, Thomas R, Christoffersen, Poul, Doyle, Samuel H, Bougamont, Marion, Schoonman, Charlotte M, Hubbard, Bryn, James, Mike R
• Format: Article in Journal/Newspaper
• Language: English
• Published: Proceedings of the National Academy of Sciences 2019
• Subjects: Greenland; glaciology; hydrology; ice sheets; lakes; Rapid Lake; glacier; greenlandic; Ice Sheet
• Online Access: https://dx.doi.org/10.17863/cam.46643; https://www.repository.cam.ac.uk/handle/1810/299570

Supraglacial lake drainage events influence Greenland Ice Sheet dynamics on hourly to interannual timescales. However, direct observations are rare, and, to date, no in situ studies exist from fast-flowing sectors of the ice sheet. Here, we present observations of a rapid lake drainage event at Store Glacier, west Greenland, in 2018. The drainage event transported 4.8 × 106 m3 of meltwater to the glacier bed in ∼5 h, reducing the lake to a third of its original volume. During drainage, the local ice surface rose by 0.55 m, and surface velocity increased from 2.0 m⋅d-1 to 5.3 m⋅d-1 Dynamic responses were greatest ∼4 km downstream from the lake, which we interpret as an area of transient water storage constrained by basal topography. Drainage initiated, without any precursory trigger, when the lake expanded and reactivated a preexisting fracture that had been responsible for a drainage event 1 y earlier. Since formation, this fracture had advected ∼500 m from the lake's deepest point, meaning the lake did not ...