Subsurface Warming of the West Antarctic Continental Shelf Linked to El Niño‐Southern Oscillation

• Published in: Geophysical Research Letters
• Main Authors: Maurice F. Huguenin, Ryan M. Holmes, Paul Spence, Matthew H. England
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: El Niño‐Southern Oscillation; West Antarctica; ocean warming; ocean‐sea ice modeling; interannual variability; Geophysics. Cosmic physics; QC801-809; Amundsen Sea; Antarc*; Antarctic; Antarctica; Ice Shelves; Sea ice
• Online Access: https://doi.org/10.1029/2023GL104518; https://doaj.org/article/61d181386985401b9d71d3ccd80328b8

Abstract Recent observations suggest that El Niño–Southern Oscillation (ENSO) impacts basal melting of West Antarctic ice shelves, yet sparse ocean observations limit our understanding of the associated processes. Here we investigate how ENSO events modulate subsurface West Antarctic shelf temperatures using high‐resolution global ocean‐sea ice model simulations. During El Niño, the subsurface shelf warming between 150 m and the shelf bottom can be up to 0.5°C in front of ice shelves. This warming arises from a weaker Amundsen Sea Low (ASL) and weaker coastal easterlies that reduce on‐shelf Ekman transport of cold surface waters, enabling enhanced transport of warm Circumpolar Deep Water (CDW) onto the shelf. A largely opposite response occurs during La Niña, with a stronger ASL and stronger Ekman transport that results in less cross‐shelf CDW transport and cooling in the subsurface. These findings have implications for interpreting basal melting on interannual to decadal time‐scales in West Antarctica.