Connectivity Between Primary and Secondary Subglacial Drainage Subsystems Beneath a Land-Terminating Outlet Glacier of the Greenland Ice Sheet

Ing, R, Bagshaw, E, Hawkins, J, Peacey, M, Doyle, S, Livingstone, S, Prior-Jones, M, Thorpe, S, Moffatt, A, Sole, A, Bianchi, G, Booth, A, Buzzard, S, Chudley, T, Clason, C, Craw, L, Edwards, L ORCID: 0000-0001-9936-6966, Gimbert, F, Hepburn, A, Jones, A et al (2026) Connectivity Between Primary and Secondary Subglacial Drainage Subsystems Beneath a Land-Terminating Outlet Glacier of the Greenland Ice Sheet. AGU Advances, 7 (5). ISSN 2576-604X

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Abstract

The evolution and connectivity of subglacial drainage systems control basal sliding and therefore modulate ice motion, yet direct observations of these systems remain limited. Here, we investigate hydraulic connectivity and its influence on ice motion at Isunnguata Sermia, a large land-terminating outlet glacier of the Greenland Ice Sheet. We use “Cryoegg” wireless sensors to obtain moulin water pressure and electrical conductivity, in conjunction with passive seismics to measure glacio-hydraulic tremor and GNSS-derived measurements of ice motion. We identify rapid switching (<24 hr) of subglacial hydraulic connectivity between distinct subsystems: a large, primary drainage axis located in a deep trough, and secondary subglacial channels. When surface melt inputs are high, the secondary subsystem fed by the instrumented moulins connects with the efficient primary drainage axis and exhibits smoothed diurnal variability and synchronization with regional ice motion and seismic tremor. When surface melt decreases, hydraulic connectivity is reduced, and the secondary subsystem becomes disconnected and responds sensitively to variations in local melt inputs, increasing local meltwater residence time. Regional ice motion is controlled by the characteristics of the primary drainage axis and is insensitive to local inputs into the secondary subsystem.

Item Type:	Article
Uncontrolled Keywords:	subglacial hydrology; ice sheets; dynamics; glaciers; 37 Earth Sciences; 3709 Physical Geography and Environmental Geoscience; 3705 Geology; 3702 Climate change science; 3705 Geology; 3709 Physical geography and environmental geoscience
Subjects:	G Geography. Anthropology. Recreation > G Geography (General) G Geography. Anthropology. Recreation > GB Physical geography G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions:	Biological and Environmental Sciences (from Sep 19)
Publisher:	Wiley
Date of acceptance:	6 August 2026
Date of first compliant Open Access:	24 September 2026
Date Deposited:	24 Sep 2026 10:15
Last Modified:	24 Sep 2026 10:15
DOI or ID number:	10.1029/2026AV002403
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29527

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