Coastal Polynyas Enable Transitions Between High and Low West Antarctic Ice Shelf Melt Rates
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1.
California Institute of Technology
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2.
Stanford University
Abstract
Melt rates of West Antarctic ice shelves in the Amundsen Sea track large decadal variations in the volume of warm water at their outlets. This variability is generally attributed to wind‐driven variations in warm water transport toward ice shelves. Inspired by conceptual representations of the global overturning circulation, we introduce a simple model for the evolution of the thermocline, which caps the warm water layer at the ice‐shelf front. This model demonstrates that interannual variations in coastal polynya buoyancy forcing can generate large decadal‐scale thermocline depth variations, even when the supply of warm water from the shelf‐break is fixed. The modeled variability involves transitions between bistable high and low melt regimes, enabled by feedbacks between basal melt rates and ice front stratification strength. Our simple model captures observed variations in near‐coast thermocline depth and stratification strength, and poses an alternative mechanism for warm water volume changes to wind‐driven theories.
Copyright and License
© 2023 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Data Availability
Data and code required to reproduce all figures in the main text and Supporting Information provided at https://doi.org/10.5281/zenodo.7987113. A binder environment (see https://mybinder.org/ for details) has been constructed so that readers can open, edit, and execute all code from a browser (click “launch binder” button on the GitHub repository home page linked to the listed doi). Editing within the binder environment will not alter the original file, so readers should feel free to manipulate provided code.
Funding
RM acknowledges the support of the General Sir John Monash Foundation. AT acknowledges support from NSF grants OPP-1644172 and OCE-2023259. EW acknowledges support from Caltech's Terrestrial Hazard Observations and Reporting Center.
Acknowledgement
We thank Michael Schodlock and Mar Flexas for their assistance in accessing and utilizing WAIS 1080 output. We thank Channing Prend and Ryan Eusebi for their helpful comments on the initial manuscript. We also thank Kevin Speer and Alessandro Silvano for helpful conversations. Finally, we acknowledge valuable work performed in the collection, collation and open access publishing of shipborne observational data by the Marine Geoscience Data System (MGDS), the Korean Polar Data Center (KPDC), and the authors of Jenkins et al. (2018).
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Additional details
- National Science Foundation
- OPP‐1644172
- National Science Foundation
- OCE‐2023259
- California Institute of Technology
- National Science Foundation
- Accepted
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2023-05-30Manuscript Accepted
- Available
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2023-08-10Published online
- Caltech groups
- Division of Geological and Planetary Sciences
- Publication Status
- Published