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126945 Roach_et_al-2018-Journal_of_Geophysical_Research__Oceans.pdf (2.73 MB)

Global observations of horizontal mixing from Argo float and surface drifter trajectories

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journal contribution
posted on 2023-05-19, 19:14 authored by Christopher RoachChristopher Roach, Balwada, D, Speer, K

Mixing by mesoscale eddies in the ocean plays a major role in setting the distribution of oceanic tracers, with important implications for physical and biochemical systems at local to global scales. Roach et al. (2016; demonstrated that a two‐particle analysis of Argo trajectories produces robust estimates of horizontal mixing in the Southern Ocean. Here we extend this analysis to produce global 1° × 1° maps of eddy diffusivity at the nominal Argo parking depth of 1,000 m. We also applied this methodology to estimate surface eddy diffusivities from Global Drifter Program (GDP) surface drifters. The global mean eddy diffusivity was 543 ± 155 m2/s at 1,000 m and 2637 ± 311 m2/s at the surface, with elevated diffusivities in regions of enhanced eddy kinetic energy, such as western boundary currents and along the Antarctic Circumpolar Current. The eddy kinetic energy at the equator is high at both the surface and depth, but the eddy diffusivity is only enhanced near the surface. At depth the eddy diffusivity is strongly suppressed due to the presence of mean flow. We used our observational estimates to test the validity of an eddy diffusivity parameterization that accounts for mixing suppression in the presence of zonal mean flows. Our results indicated that this parameterization generally agrees with the directly observed eddy diffusivities in the midlatitude and high‐latitude oceans.


Publication title

Journal of Geophysical Research: Oceans










Institute for Marine and Antarctic Studies


Wiley-Blackwell Publishing Inc.

Place of publication

United States

Rights statement

©2018. American Geophysical Union. All Rights Reserved.

Repository Status

  • Restricted

Socio-economic Objectives

Antarctic and Southern Ocean oceanic processes; Oceanic processes (excl. in the Antarctic and Southern Ocean)

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