Baroclinic Ocean Response to Climate Forcing Regulates Decadal Variability of Ice‐Shelf Melting in the Amundsen Sea

• Published in: Geophysical Research Letters
• Main Authors: Silvano, Alessandro, Holland, Paul R., Naughten, Kaitlin A., Dragomir, Oana, Dutrieux, Pierre, Jenkins, Adrian, Si, Yidongfang, Stewart, Andrew L., Peña Molino, Beatriz, Janzing, Gregor W., Dotto, Tiago S., Naveira Garabato, Alberto C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Amundsen Sea; Pacific; Ice Shelf; Ice Shelves
• Online Access: http://nora.nerc.ac.uk/id/eprint/533728/; https://nora.nerc.ac.uk/id/eprint/533728/1/Geophysical%20Research%20Letters%20-%202022%20-%20Silvano%20-%20Baroclinic%20Ocean%20Response%20to%20Climate%20Forcing%20Regulates%20Decadal%20Variability.pdf; https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL100646

Warm ocean waters drive rapid ice-shelf melting in the Amundsen Sea. The ocean heat transport toward the ice shelves is associated with the Amundsen Undercurrent, a near-bottom current that flows eastward along the shelf break and transports warm waters onto the continental shelf via troughs. Here we use a regional ice-ocean model to show that, on decadal time scales, the undercurrent's variability is baroclinic (depth-dependent). Decadal ocean surface cooling in the tropical Pacific results in cyclonic wind anomalies over the Amundsen Sea. These wind anomalies drive a westward perturbation of the shelf-break surface flow and an eastward anomaly (strengthening) of the undercurrent, leading to increased ice-shelf melting. This contrasts with shorter time scales, for which surface current and undercurrent covary, a barotropic (depth-independent) behavior previously assumed to apply at all time scales. This suggests that interior ocean processes mediate the decadal ice-shelf response in the Amundsen Sea to climate forcing.