Atmosphere Ocean Science Friday Seminar

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Effects of Ambient Currents and Tides on Melting at the Grounding Line of Thwaites Glacier

Speaker: Mainak Mondal

Location: Warren Weaver Hall 1314

Date: Friday, April 25, 2025, 4 p.m.

Synopsis:

The stability of Thwaites Glacier’s grounding line is critical for understanding the West Antarctic Ice Sheet’s future and its contribution to sea-level rise. While warm water intrusions are a well-known driver of melting, the role of shore-parallel ambient currents and periodic tidal forcing remains underexplored. Using a high-resolution, idealized MITgcm setup, we model the grounding zone cavity to investigate how along-shelf ambient currents, and tides influence circulation and melting patterns.
Our results show that even modest ambient currents disrupt classical buoyancy-driven circulation by introducing Ekman layers and geostrophic flows that redistribute heat and salt. Positive along-shelf gradients enhance melting throughout the cavity, while negative gradients reduce melt rates except near the grounding line. Periodic tidal forcing further modifies the system, generating a residual circulation layer that enhances vertical mixing and alters the delivery of heat to the ice-ocean interface. This interplay of tidal forcing and ambient currents significantly impacts melt patterns and grounding-line stability.
These findings highlight the need to incorporate realistic three-dimensional ocean dynamics, including tides and residual circulation, into grounding-zone models. By linking shore-parallel flows, tides, and stratified dynamics with melting processes, this study provides new insights into Thwaites Glacier’s retreat and underscores the importance of small-scale ocean variability in ice-ocean interactions.