Southern Ocean deep convection as a driver of Antarctic warming events

• Published in: Geophysical Research Letters
• Main Authors: Pedro, J. B., Martin, Torge, Steig, E. J., Jochum, M., Park, Wonsun, Rasmussen, S. O.
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 2016
• Subjects: Antarctic; Southern Ocean; Antarc*; Antarctica; ice core; Sea ice
• Online Access: https://oceanrep.geomar.de/id/eprint/31516/; https://oceanrep.geomar.de/id/eprint/31516/1/grl54088.pdf; https://oceanrep.geomar.de/id/eprint/31516/2/grl54088-sup-0001-supinfo.pdf; https://oceanrep.geomar.de/id/eprint/31516/13/grl54088.pdf; https://doi.org/10.1002/2016GL067861

Simulations with a free-running coupled climate model show that heat release associated with Southern Ocean deep convection variability can drive centennial-scale Antarctic temperature variations of up to 2.0 °C. The mechanism involves three steps: Preconditioning: heat accumulates at depth in the Southern Ocean; Convection onset: wind and/or sea-ice changes tip the buoyantly unstable system into the convective state; Antarctic warming: fast sea-ice–albedo feedbacks (on annual–decadal timescales) and slow Southern Ocean frontal and sea-surface temperature adjustments to convective heat release (on multidecadal–century timescales) drive an increase in atmospheric heat and moisture transport toward Antarctica. We discuss the potential of this mechanism to help drive and amplify climate variability as observed in Antarctic ice-core records.