Suppression of eddy diffusivity across jets in the Southern Ocean

• Published in: Journal of Physical Oceanography
• Main Authors: Ferrari, R, Nikurashin, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Meteorological Soc 2010
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://doi.org/10.1175/2010JPO4278.1; http://ecite.utas.edu.au/79717

Geostrophic eddies control the meridional mixing of heat, carbon, and other climatically important tracersin the Southern Ocean. The rate of eddy mixing is typically quantified through an eddy diffusivity. There is anongoing debate as to whether eddy mixing in enhanced in the core of the Antarctic Circumpolar Current or onits flanks. A simple expression is derived that predicts the rate of eddy mixing, that is, the eddy diffusivity, asa function of eddy and mean current statistics. This novel expression predicts suppression of the cross-jet eddydiffusivity in the core of the Antarctic Circumpolar Current, despite enhanced values of eddy kinetic energy.The expression is qualitatively and quantitatively validated by independent estimates of eddy mixing fromaltimetry observations. This work suggests that the meridional eddy diffusivity across the Antarctic CircumpolarCurrent is weaker than presently assumed because of the suppression of eddy mixing by the strongzonal current.