Publication:
Geophysical Research Letters;pp. 1948-1954

Publication type:
Article

Abstract:

Observations show that radii of oceanic eddies often exceed the Rossby radius of deformation, whereas theoretical studies suggest that such vortices should be unstable. The present paper resolves this paradox by presenting a wide class of large geostrophic vortices with a sign-definite gradient of potential vorticity (which makes them stable), in an ocean where the density gradient is mostly confined to a thin near-surface layer (which is indeed the case in the real ocean). The condition of a thin "active" layer is what makes the present work different from the previous theoretical studies and is of utmost importance. It turns out that without it, the joint requirement that a vortex be large and have a sign-definite potential vorticity gradient trivializes the problem by eliminating all vortices except nearly barotropic ones.

Benilov, Eugene(European Geosciences Union (EGU) International, 1999)

The evolution of tracer "injected" into an equivalent barotropic eddy on the beta-plane is examined numerically. The eddy is governed by the standard quasigeostrophic equation, and the concentration of tracer is governed ...

We examine the stability of a vertical liquid bridge between two vertically vibrating, coaxial disks. Assuming that the vibration amplitude and period are much smaller than the mean distance between the disks and the global ...

Haynes, M; O'Brien, Stephen B.G.; Benilov, Eugene(AIP Publishing, 2016)

This paper uses asymptotic techniques to find the shape of a two dimensional liquid bridge suspended between two vertical walls. We model the equilibrium bridge shape using the Laplace-Young equation. We use the Bond number ...

Benilov, Eugene; Barros, Ricardo; O'Brien, Stephen B.G.(American Physical Society, 2016)

We investigate the stability of thin liquid curtains with respect to two-dimensional perturbations. The dynamics of perturbations with wavelengths exceeding (or comparable to) the curtain's thickness are examined using the ...

This paper presents a model which yields examples of stable vortices in a continuously
stratified rotating fluid, thus providing a possible explanation of the observed longevity of oceanic
eddies. The model is based on ...