Quantitative controls on the routing of supraglacial meltwater to the bed of glaciers and ice sheets

• Main Author: Clason, Caroline
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Geography and Environment, University of Aberdeen 2012
• Subjects: Glaciers Greenland Moulins Supraglacial Crevasses Modelling; Physical Geography; Naturgeografi; Arctic; Canada; Croker; Croker Bay; Devon Ice Cap; Greenland; Leverett Glacier; glacier; glacier*; Ice cap; Ice Sheet
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-85178

The influence of seasonal influx of supraglacial meltwater on basal water pressures and consequent changes in ice surface velocity has been a focus of research spanning over three decades, particularly focussing on alpine glaciers. Now, with increased recognition for a need to better include glacial hydrology within models of ice dynamics and ice sheet evolution, the ability to predict where and when meltwater is delivered to the subglacial system is paramount, both for understanding the dynamics of alpine glaciers, and of large Arctic ice masses. Studies of the dynamics of outlet glaciers on the Greenland Ice Sheet have received particular attention in recent years, as links between ice acceleration and increased surface melt production are explored. Responses of horizontal and vertical ice velocities to meltwater generated suggest efficient transmission of meltwater from the supraglacial to subglacial hydrological systems. Indeed, in the case of meltwater transfer through the drainage of supraglacial lakes, it has been shown that such build-ups of stored meltwater can force crevasse penetration through many hundreds of metres of ice. This thesis presents a new modelling routine for the prediction of moulin formation and delivery of meltwater to the ice-bed interface. Temporal and spatial patterns of moulin formation through propagation of crevasses and drainage of supraglacial lakes are presented, and quantitative controls on water-driven crevasse propagation are investigated through a series of sensitivity tests. The model is applied to two glacial catchments: the Croker Bay catchment of Devon Ice Cap in High Arctic Canada; and Leverett Glacier catchment of the southwest Greenland Ice Sheet. Through model application to these sites, sensitivities to crevasse surface dimensions, ice tensile strength, ice fracture toughness and enhanced production of surface meltwater are investigated. Model predictions of moulin formation are compared with field observations and remotely sensed data, including ice surface ...