Forcing of the overturning circulation across a circumpolar channel by internal wave breaking

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Broadbridge, Maria B., Naveira Garabato, Alberto C., Nurser, A.J. George
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Marine Sciences; Southern Ocean
• Online Access: http://nora.nerc.ac.uk/id/eprint/513884/; https://nora.nerc.ac.uk/id/eprint/513884/7/jgrc21824.pdf; https://nora.nerc.ac.uk/id/eprint/513884/1/jgrc21824.pdf; https://doi.org/10.1002/2015JC011597

The hypothesis that the impingement of mesoscale eddy flows on small-scale topography regulates diapycnal mixing and meridional overturning across the deep Southern Ocean is assessed in an idealised model. The model simulates an eddying circumpolar current coupled to a double-celled meridional overturning with properties broadly resembling those of the Southern Ocean circulation, and represents lee wave-induced diapycnal mixing using an online formulation grounded on wave radiation theory. The diapycnal mixing generated by the simulated eddy field is found to play a major role in sustaining the lower overturning cell in the model, and to underpin a significant sensitivity of this cell to wind forcing. The vertical structure of lower overturning is set by mesoscale eddies, which propagate the effects of near-bottom diapycnal mixing by displacing isopycnals vertically.