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The identification of vortices in a fluid flow is a dynamically interesting problem that has practical applications in oceanography due to the outsized role eddies play in water mass, heat, and tracer transport. Here a new Eulerian scheme is developed to detect both vortices and strongly strained fronts, which are both ubiquitous in the World Ocean. The new scheme is conceptually linked to the well-known Okubo–Weiss parameter, but is extended to quasigeostrophic flows by recognizing the strong role played by vertical shear in ocean dynamics. Adapted from the λ 2 criterion for vortex identification, the scheme considers the curvature of the pressure field as the differentiator between vortical and strained flow structures, and it is shown that its underlying geometry also exhibits characteristics of quasigeostrophic flow. The uses and skill of the scheme are demonstrated using a high-resolution regional ocean simulation, and prospects for its use with observational products are discussed. [ABSTRACT FROM AUTHOR]

Ocean ventilation is the process by which climatically important tracers such as heat and carbon are exchanged between the atmosphere and ocean interior. In this paper a series of numerical simulations are used to study the interaction of submesoscales and a topographically steered jet in driving rapid ventilation. The ventilation is found to increase both as a function of wind stress and model resolution, with a submesoscale-resolving 1/1208 model exhibiting the largest ventilation rate. The jet in this simulation is found to be persistently unstable to submesoscale instabilities, which are known to feature intense vertical circulations. The vertical tracer transport is found to scale as a function of the eddy kinetic energy and mean isopycnal slope, whose behaviors change as a function of the wind stress and due to the emergence of a strong potential vorticity gradient due to the lateral shear of the jet. These results highlight the importance of jet- submesoscale interaction as a bridge between the atmosphere and the ocean interior. [ABSTRACT FROM AUTHOR]

Oceanic mesoscale eddies are known to diffuse and stir tracers, and the development of skillful eddy closures is aided considerably by the accurate diagnosis of these processes from eddy‐resolving model statistics. In this work a multiple‐tracers inversion method is applied to a global mesoscale eddy‐resolving simulation, with the intent to solve for the eddy transport tensor that describes the eddy diffusion (symmetric part) and stirring (antisymmetric part). Special emphasis is placed on diagnosing the anisotropy of the horizontal transport, which is described by the eigenvalues and eigenvectors of the 2×2 horizontal symmetric subtensor. Global diagnoses of these quantities, along with an examination of their vertical structures, are used to recommend an algorithm for extending the Gent and McWilliams and Redi parameterizations to include anisotropic effects. Plain Language Summary: Tracer transport by ocean mesoscale eddies is usually parameterized using a flux‐gradient relationship with a scalar transport coefficient for the horizontal fluxes. Using a scalar coefficient implies that the transport is horizontally isotropic. There exist many mechanisms that may lead to anisotropic transport, however, and parameterizing this anisotropy requires a (symmetric) tensor coefficient. We diagnose this tensor coefficient using a high‐resolution global ocean model with an inversion method that uses multiple passive tracers. The statistics from the diagnosis allow us to explore the properties of the flow that govern the anisotropy, and to recommend an anisotropic extension of extant tracer parameterization schemes. Key Points: Anisotropic eddy diffusivity is diagnosed with a multiple tracers inversion techniqueAn eigendecomposition of the horizontal diffusion tensor determines the 3‐D parameterized transportThis diagnosis informs an anisotropic extension to the GM‐Redi parameterization [ABSTRACT FROM AUTHOR]