Date of Award

Spring 1-1-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Harihar Rajaram

Second Advisor

Robert Anderson

Third Advisor

Waleed Abdalati

Fourth Advisor

Mathieu Morlighem

Fifth Advisor

Matthew Hoffman

Abstract

Accurate projections of future sea level rise require detailed modeling of the relevant processes affecting glacier and ice sheet dynamics. Although sophisticated high-resolution ice sheet models have been developed in recent years, some processes are still not well understood. Through a combination of field experiments, numerical modeling, and theoretical analyses, this research explores several processes affecting dynamics of the Greenland ice sheet, particularly in a changing climate as melt increases further inland: a) A novel, low-cost in-situ method of inferring firn permeability is presented, which is especially useful in regions of the ice sheet experiencing increased melt and refrozen solid ice layers in the firn. b) Thermo-mechanically coupled flow line modeling of the Greenland ice sheet interior reveals insights about the distribution of temperate ice and sensitivity to different modeling parameters. c) A subglacial hydrology model is introduced (SHAKTI: Subglacial Hydrology and Kinetic, Transient Interactions) that allows for the coexistence of laminar and turbulent flow regimes and flexible geometry configurations that include both sheetlike and channelized drainage systems, while including melt from viscous dissipation. Application of the SHAKTI model to marine-terminating Store Glacier in west Greenland suggests a channelized system develops near the terminus with high meltwater input and collapses to a sheetlike system with low input, with some residual channel structure extending inland from the front. d) Heat transfer coefficients are obtained through modeling of internal viscous and turbulent dissipation (appropriate for subglacial and englacial hydrology) compared to the case of heated walls (the classical experimental case upon which most heat transfer coefficients are based). A difference of about a factor of two is found between the heat transfer coefficients for heated walls and the internal dissipation case.

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