Long‐Term Support of an Active Subglacial Hydrologic System in Southeast Greenland by Firn Aquifers

• Published in: Geophysical research letters Vol. 46; no. 9; pp. 4772 - 4781
• Main Authors: Poinar, Kristin, Dow, Christine F, Andrews, Lauren C
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center American Geophysical Union 16-05-2019; John Wiley & Sons, Inc
• Subjects: Aquifers; Bare ice; Channeling; Channelization; Delay; Drainage systems; Earth Resources And Remote Sensing; Evolution; Firn; firn aquifer; Glaciation; Glacier flow; Glaciers; Glaciohydrology; Greenland Ice Sheet; Hydrologic models; Hydrology; Hydrostatic pressure; Ice; Ice environments; ice sheet hydrology; Ice sheets; Measuring instruments; Meltwater; Pressure; Regions; Sea level; Seasonal variation; Seasonal variations; subglacial hydrology; Subglacial water; Water pressure; Water supply; Greenland
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2019GL082786

The state of the subglacial hydrologic system, which can modify ice motion, is sensitive to the volume and rate of meltwater reaching it. Bare-ice regions rapidly transport meltwater to the bed via moulins, while in certain accumulation-zone regions, meltwater first flows through firn aquifers, which can introduce a substantial delay. We use a subglacial hydrological model forced with idealized meltwater input scenarios to test the effect of this delay on subglacial hydrology. We find that addition of firn-aquifer water to the subglacial system elevates the inland subglacial water pressure while reducing water pressure and enhancing subglacial channelization near the terminus. This effect dampens seasonal variations in subglacial water pressure and may explain regionally anomalous ice-velocity patterns observed in Southeast Greenland. As surface melt rates increase and firn aquifers expand inland, it is crucial to understand how inland drainage of meltwater affects the evolution of the subglacial hydrologic system.