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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.
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This content will become publicly available on November 8, 2025
Ross Ice Shelf frontal zone subjected to increasing melting by ocean surface waters
Solar-warmed surface waters subduct beneath Antarctica’s ice shelves as a result of wind forcing, but this process is poorly observed and its interannual variability is yet to be assessed. We observe a 50-meter-thick intrusion of warm surface water immediately beneath the Ross Ice Shelf. Temperature in the uppermost 5 meters decreases toward the ice base in near-perfect agreement with an exponential fit, consistent with the loss of heat to the overlying ice. Ekman forcing drives a heat transport into the cavity sufficient to contribute considerably to near-front melting; this transport has increased over the past four decades, driven by the increasing heat content of the ice-front polynya. Interannual variability of the heat transport is driven by zonal wind stress. These results provide a benchmark against which model performance may be assessed as we seek to reduce uncertainty around the contribution of basal melting to sea level rise.
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- Award ID(s):
- 2040571
- PAR ID:
- 10561047
- Publisher / Repository:
- Journal of Geophysical Research: Oceans
- Date Published:
- Journal Name:
- Science Advances
- Volume:
- 10
- Issue:
- 45
- ISSN:
- 2375-2548
- Subject(s) / Keyword(s):
- ice shelf glider
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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