Decadal variability of ice-shelf melting in the Amundsen Sea driven by sea-ice freshwater fluxes

• Published in: Geophysical Research Letters
• Main Authors: Haigh, Michael, Holland, Paul R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2024
• Subjects: West Antarctica; Amundsen Sea; Pacific; Antarc*; Antarctica; Ice Shelf; Ice Shelves; Sea ice
• Online Access: http://nora.nerc.ac.uk/id/eprint/536808/; https://nora.nerc.ac.uk/id/eprint/536808/1/Geophysical%20Research%20Letters%20-%202024%20-%20Haigh%20-%20Decadal%20Variability%20of%20Ice%E2%80%90Shelf%20Melting%20in%20the%20Amundsen%20Sea%20Driven%20by.pdf; https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL108406

The ice streams flowing into the Amundsen Sea, West Antarctica, are losing mass due to changes in oceanic basal melting of their floating ice shelves. Rapid ice-shelf melting is sustained by the delivery of warm Circumpolar Deep Water to the ice-shelf cavities, which is first supplied to the continental shelf by an undercurrent that flows eastward along the shelf break. Temporal variability of this undercurrent controls ice-shelf basal melt variability. Recent work shows that on decadal timescales the undercurrent variability opposes surface wind variability. Using a regional model, we show that undercurrent variability is induced by sea-ice freshwater fluxes, particularly those north of the shelf break, which affect the cross-shelf break density gradient. This sea-ice variability is linked to tropical Pacific variability impacting atmospheric conditions over the Amundsen Sea. Ice-shelf melting also feeds back onto the undercurrent by affecting the on-shelf density, thereby influencing shelf-break density gradient anomalies.