Hetonic quartets in a two-layer quasi-geostrophic flow: V-states and stability

Type Article
Date 2018-05
Language English
Author(s) Reinaud J. N.1, Sokolovskiy M. A.2, 3, Carton Xavier4
Affiliation(s) 1 : Univ St Andrews, Math Inst, St Andrews KY16 9SS, Fife, Scotland.
2 : Russian Acad Sci, Inst Water Problems, 3 Gubkina St, Moscow 119333, Russia.
3 : Russian Acad Sci, Shirshov Inst Oceanol, 36 Nahimovskiy Prospekt, Moscow 117997, Russia.
4 : UBO UBL, IUEM, Lab Oceanog Phys & Spatiale, Technopole Brest Iroise, F-29280 Plouzane, France.
Source Physics Of Fluids (1070-6631) (Amer Inst Physics), 2018-05 , Vol. 30 , N. 5 , P. 056602 (8p.)
DOI 10.1063/1.5027181
WOS© Times Cited 2
Abstract

We investigate families of finite core vortex quartets in mutual equilibrium in a two-layer quasi-geostrophic flow. The finite core solutions stem from known solutions for discrete (singular) vortex quartets. Two vortices lie in the top layer and two vortices lie in the bottom layer. Two vortices have a positive potential vorticity anomaly, while the two others have negative potential vorticity anomaly. The vortex configurations are therefore related to the baroclinic dipoles known in the literature as hetons. Two main branches of solutions exist depending on the arrangement of the vortices: the translating zigzag-shaped hetonic quartets and the rotating zigzag-shaped hetonic quartets. By addressing their linear stability, we show that while the rotating quartets can be unstable over a large range of the parameter space, most translating quartets are stable. This has implications on the longevity of such vortex equilibria in the oceans.

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