EES Seminar (In Person): Ice sheet instability and the potential importance of subglacial hydrology
Doctoral Candidate, Dept. Physics & Physical Oceanography
Memorial University of Newfoundland, St John's, Canada
Ice sheet instability and the potential importance of subglacial hydrology
Abstract: Ice sheet instability largely depends on small portions of the ice which flow orders of magnitude faster (10’s km/yr vs 1’s m/yr) than the rest, termed ice streams. Though Antarctic ice streams comprise less than 10% of the ice sheet area, 90% of drainage goes through them. Herein lies a major hurdle to understanding the continental scale: a nonlinear dependence on smaller scale system components (e.g. those occurring at the bed) and the representation of those finer features at the continental level.
Surging – the formation and acceleration of ice streams – likely involves thermal hydraulic feedbacks. Meltwater generation at the ice base reduces friction while more rapidly deforming ice produces more meltwater. The type of melt water drainage system most relevant at continental scales is unclear and several have been described. I will show that subglacial hydrology is crucial to surge-type ice dynamics but the details of those physics are not. Subglacial hydrology also dictates how an ice sheet modifies its bed and consequently its basal friction regime. I will also examine the hydrologic control on glacial transport of sediment and erosion of bedrock.
The ice sheet model used for these experiments uses 3D thermo-mechanically coupled ice deformation with fully coupled subglacial hydrology and glacial sediment production/transport. The simplified climate and domain mimic the North American setting without confounding factors from topography, true land-sea mask, and spatiotemporally varying climate. I examine the contribution from subglacial hydrology to large-scale periodic surging through the Hudson Strait (an hypothesis for the origin of Heinrich events), southern margin advance, and ice stream formation. I will also show how hydrology is responsible for episodic sediment transport in this setting.
IN PERSON: Milligan Room (8th floor of Biology/EES wing of LSC)
NOTE: Coffee and Doughnuts will be Available
Online via Zoom (Please contact the department at firstname.lastname@example.org for the Zoom link.)