Variability in ice motion at a land-terminating Greenlandic outlet glacier: the role of channelized and distributed drainage systems

• Published in: Journal of Glaciology
• Main Authors: TOM COWTON, PETER NIENOW, ANDREW SOLE, IAN BARTHOLOMEW, DOUGLAS MAIR
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2016
• Subjects: glacier hydrology; ice dynamics; subglacial processes; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; greenlandic; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2016.36; https://doaj.org/article/6d33aada6e1f459289eaab8a58ff5fa2

We use a combination of field observations and hydrological modelling to examine the mechanisms through which variability in meltwater input affects ice motion at a land-terminating Greenlandic outlet glacier. We find a close agreement between horizontal ice velocity, vertical ice velocity and modelled subglacial water pressure over the course of a melt season. On this basis, we argue that variation in horizontal and vertical ice velocity primarily reflects the displacement of basal ice during periods of cavity expansion and contraction, a process itself driven by fluctuations in basal water pressure originating in subglacial channels. This process is not captured by traditional sliding laws linking water pressure and basal velocity, which may hinder the simulation of realistic diurnal to seasonal variability in ice velocity in coupled models of glacial hydrology and dynamics.