A note on estimating eddy diffusivity for oceanic double-diffusive convection

Haruka Nakano, Jiro Yoshida

Research output: Contribution to journalReview articlepeer-review

13 Citations (Scopus)


In this note, we provide an overview of the theoretical, numerical, and observational studies focused on oceanic eddy diffusivity, with an emphasis on double-diffusive convection (DDC). DDC, when calculated using the turbulent kinetic energy (TKE) equation, produces a negative diffusion of density. A second-moment closure model shows that DDC is effective within a narrow range. Other parameterizations can use in the actual sea, but improvements are still needed. Mixing coefficients referring to mixing efficiency are key factors when distinguishing DDC from conventional turbulence. Here, we show that measurements involving the gradient Richardson number, the buoyancy Reynolds number, and density ratio play a crucial role in determining eddy diffusivity in the presence of DDC. Therefore, deployment of a microstructure profiler together with either an acoustic Doppler current profiler (ADCP), lowered ADCP, or electromagnetic current meter is essential when measuring eddy diffusivity in the ocean’s interior.

Original languageEnglish
Pages (from-to)375-393
Number of pages19
JournalJournal of Oceanography
Issue number5
Publication statusPublished - Oct 1 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oceanography


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