The Stability of the Drygalski Ice Tongue

• Main Author: Indrigo, Christine
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2020
• Subjects: Glaciology; Ice tongues; Subglacial hydrology; Remote sensing; Numerical modelling; Antarctica; Hydrologic models; Subglacial lakes; Aerial exploration; Antarctic; Buttress; David Glacier; Drygalski; Drygalski Ice Tongue; East Antarctica; Ross Sea; Terra Nova Bay; The Antarctic; Antarc*; Ice Sheet; Ice Shelves; Sea ice
• Online Access: http://hdl.handle.net/10012/15585

Antarctica has the potential to contribute to sea-level rise by up to 58 m if it were to entirely melt. The Antarctic Ice Sheet is fringed by floating ice in the form of ice shelves and ice tongues, which help to buttress and slow the flow of grounded ice into the ocean. Monitoring the stability of these ice shelves and ice tongues is increasingly important in a warming world, as several areas of floating ice across Antarctica are already experiencing considerable mass loss and thinning due to warming air and ocean conditions. The primary goal of this thesis is to examine several factors contributing to the stability of the Drygalski Ice Tongue in East Antarctica using a combination of remote sensing imagery analysis and subglacial hydrology modelling. The Drygalski Ice Tongue is ~140 km long with an unconfined length of 90 km extending into the Ross Sea. This unconfined length influences local ocean conditions and has a significant control on the size of the nearby Terra Nova Bay polynya, keeping the area free of sea ice. The ice tongue has experienced three large scale calving events in its recorded history since the early 1900s. In this study, Landsat imagery from 1988 to 2018 is used to track the advance of the ice tongue, marginal fracture propagation, and to derive velocity using manual feature tracking. The Glacier Drainage Systems (GlaDS) model is applied to the David Glacier catchment, which feeds into the ice tongue, to reveal the locations and discharge from subglacial channels along the grounding line. These channels are compared with basal channels beneath the floating ice tongue that are identified using airborne radar-derived ice thickness and hydrostatically-derived ice thickness, which can reveal channels in basal draft beneath the ice tongue. The results of this study propose a cyclical relationship between the occurrence of large calving events and large marginal fracture formation, in which large calving events result in the formation of new large fractures where the ice tongue emerges from ...