PhD Thesis Proposal: Hyoeun Shim

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"The impact of episodic subglacial discharge on basal melt and grounding line retreat for warm antarctic ice shelves"

Abstract

Ice shelves in the Amundsen Sea Embayment (ASE) have been thinning rapidly, which accounts for the majority of the current Antarctic ice mass loss. While ocean-induced melting has been proposed to be a key driver for this enhanced thinning, an event of lake drainage beneath Thwaites Glacier followed by increased melt rates suggest that such an episodic drainage forcing can also impact the dynamic responses of the ice shelves by increasing basal melt near the grounding line. Potential of this discharge forcing to be a primary driver of long-term glacier retreat has yet to be evaluated with numerical ice-sheet models. 

This work aims at improving our understanding of the impact of subglacial freshwater discharge on ice shelf basal melt and the dynamic evolution of ASE glaciers. We propose to develop a basal melt parameterization that accounts for the impact of freshwater discharge based on a coupled plume-melt framework and a simplified expression of ice-shelf basal melt for warm water ice shelf cavities. A theoretical analysis of the meltwater plume theory as well as a comparative analysis with analytical solutions of the plume model derived in the limit of weak ocean-forced melting are performed. The resulting melt parameterization includes a number of coefficients that are calibrated based on the plume model solutions. Using this new parameterization, we aim to perform simulations of Thwaites Glacier in the ASE using the Ice-sheet and Sea-level System Model (ISSM) to assess the efficacy of the freshwater forcing in driving long-term retreat of the glacier.

Thesis Committee

• Helene Seroussi (chair)
• Colin Meyer
• Yoshihiro Nakayama
• Xylar Asay-Davis (Argonne national laboratory)

Contact

For more information, contact Thayer Registrar at thayer.registrar@dartmouth.edu.