Damping of climate-scale oceanic variability by mesoscale eddy turbulence

• Published in: Journal of Physical Oceanography
• Main Authors: Sévellec, Florian, Naveira Garabato, A. C., Huck, Thierry
• Format: Text
• Language: English
• Published: American Meteorological Society
• Subjects: envir; geo; Antarctic; Drake Passage; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://doi.org/10.1175/JPO-D-20-0141.1; https://archimer.ifremer.fr/doc/00658/77057/78356.pdf; https://archimer.ifremer.fr/doc/00658/77057/

The impact of mesoscale eddy turbulence on long-term, climatic variability in the ocean's buoyancy structure is investigated using observations from a mooring deployed in the Drake Passage, Southern Ocean. By applying the Temporal-Residual-Mean framework and characterizing the variance contributors and the buoyancy variance budget, we identify the main source and sink of long-term buoyancy variance. Long-term buoyancy variance amplitude is set by long-term vertical velocity fluctuations acting on the steady stratification. This baro-clinic buoyancy flux is also the main source of the variance, indicative of the effect of large-scale baroclinic instability. This source is balanced by a sink of long-term buoyancy variance associated with the vertical advection of the steady stratification by the eddy-induced circulation. We conclude that mesoscale eddy turbulence acts as a damping mechanism for long-term, climatic variability in the region of the observations, consistent with an ‘eddy saturated’ behaviour of the Antarctic Circumpolar Current.