Tides modulate crevasse opening prior to a major calving event at Bowdoin Glacier, Northwest Greenland

• Published in: Journal of Glaciology
• Main Authors: Eef van Dongen, Guillaume Jouvet, Andrea Walter, Joe Todd, Thomas Zwinger, Izumi Asaji, Shin Sugiyama, Fabian Walter, Martin Funk
• Format: Article
• Language: English
• Published: Cambridge University Press 2020-02-01
• Subjects: crevasses; glacier monitoring; glacier modelling; iceberg calving
• Online Access: https://www.cambridge.org/core/product/identifier/S0022143019000893/type/journal_article
• ISSN: 0022-1430; 1727-5652

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.