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Evolution of drainage system morphology at a land‐terminating Greenlandic outlet glacier
Author(s) -
Cowton Tom,
Nienow Peter,
Sole Andrew,
Wadham Jemma,
Lis Greg,
Bartholomew Ian,
Mair Doug,
Chandler Dave
Publication year - 2013
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1029/2012jf002540
Subject(s) - meltwater , geology , greenland ice sheet , drainage , ice sheet , drainage system (geomorphology) , channelized , ice stream , glacier , geomorphology , hydrology (agriculture) , glacier ice accumulation , melt pond , climatology , cryosphere , sea ice , geotechnical engineering , ecology , telecommunications , computer science , biology
The influence of meltwater on the dynamics and geomorphic impact of the Greenland Ice Sheet is strongly controlled by the morphology of the ice sheet's drainage system. However, this system and its evolution through the melt season remain poorly understood. Here we present the results of an intensive programme of dye tracing experiments undertaken along the lower 14 km of a land‐terminating Greenlandic outlet glacier over a period of four months during the 2010 melt season. These data are interpreted in conjunction with observations of proglacial discharge, englacial water storage, surface melt rates and ice velocity to produce a detailed picture of the changing hydrology of the glacier. Following the onset of melt in the spring, inputs to the drainage system regularly exceed outputs, causing the englacial water level to rise to the ice sheet surface. During this time there is a rapid transition from distributed to channelized drainage in those parts of the drainage system closed by ice deformation over winter. As the melt season progresses, channel efficiency increases and englacial storage and ice velocity decrease. High‐velocity events continue to be observed following the channelization of the drainage system however, indicating that hydrological forcing of ice velocity occurs despite the existence of channels during periods when meltwater inputs exceed the capacity of the subglacial drainage system.