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Surface cross-stream eddy diffusion in the Southern Ocean is estimated by monitoring dispersion of particles numerically advected with observed satellite altimetry velocity fields. To gain statistical significance and accuracy in the resolution of the jets, more than 1,5 million particles are released every 6 months over 16 years and advected for one year. Results are analyzed in a dynamic height coordinate system. Cross-stream eddy diffusion is highly inhomogenous. Diffusivity is larger on the equatorward flank of the Antarctic Circumpolar Current (ACC) along eddy stagnation bands, where eddy displacement speed approaches zero. Along such bands, diffusivities reach typical values of 3500 m2 s-1. Local maxima of about 8-12.103 m2 s-1 occur in the energetic western boundary current systems. In contrast, diffusivity is lower in the core of the Antarctic Circumpolar Current with values of 1500-3000 m2 s-1, and continues to decrease south of the main ACC system. The distribution of eddy diffusion is set at three scales: at circumpolar scale, the mean flow reduces diffusion in the ACC and enhances it on the equatorward side of the current; at basin scale, diffusion is enhanced in the energetic western boundary current extension regions; at regional scale, diffusion is enhanced in the wake of large topographic obstacles. We find that the zonally average structure of eddy diffusion can be explained by theory which takes mean flow into account; however, local values depend on eddy propagation, not simply described by a single wave speed, and topography.

Item Type:	Refereed Article
Keywords:	Southern Ocean, eddy, ocean dynamics
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Physical oceanography
Objective Division:	Environmental Management
Objective Group:	Management of Antarctic and Southern Ocean environments
Objective Field:	Antarctic and Southern Ocean oceanic processes
UTAS Author:	Rintoul, SR (Dr Steve Rintoul)
ID Code:	80634
Year Published:	2011
Web of Science® Times Cited:	33
Deposited By:	CRC-Antarctic Climate & Ecosystems
Deposited On:	2012-11-06
Last Modified:	2017-11-01
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