Tides modulate crevasse opening prior to a major calving event at Bowdoin Glacier, Northwest Greenland. Issue 255 (4th February 2020)

• Record Type: Journal Article
• Authors: van Dongen, Eef; Jouvet, Guillaume; Walter, Andrea; Todd, Joe; Zwinger, Thomas; Asaji, Izumi; Sugiyama, Shin; Walter, Fabian; Funk, Martin
• Is Part Of: Journal of Glaciology. Volume 66:Issue 255(2020)
• Page Start: 113
• Page End: 123
• Publication Date: 2020-02-04
• Subjects: crevasses, -- glacier monitoring, -- glacier modelling, -- iceberg calving
• DOI: 10.1017/jog.2019.89
• Languages: English
• ISSNs: 0022-1430

Abstract

Abstract: Retreat of calving glaciers worldwide has contributed substantially to sea-level rise in recent decades. Mass loss by calving contributes significantly to the uncertainty of sea-level rise projections. At Bowdoin Glacier, Northwest Greenland, most calving occurs by a few large events resulting from kilometre-scale fractures forming parallel to the calving front. High-resolution terrestrial radar interferometry data of such an event reveal that crevasse opening is fastest at low tide and accelerates during the final 36 h before calving. Using the ice flow model Elmer/Ice, we identify the crevasse water level as a key driver of modelled opening rates. Sea water-level variations in the range of local tidal amplitude (1 m) can reproduce observed opening rate fluctuations, provided crevasse water level is at least 4 m above the low-tide sea level. The accelerated opening rates within the final 36 h before calving can be modelled by additional meltwater input into the crevasse, enhanced ice cliff undercutting by submarine melt, ice damage increase due to tidal cyclic fatigue, crevasse deepening or a combination of these processes. Our results highlight the influence of surface meltwater and tides on crevasse opening leading to major calving events at grounded tidewater glaciers such as Bowdoin.