Abstract
The three-layer version of the contour dynamics/surgery method is used to study the interaction mechanisms of a large-scale surface vortex with a smaller vortex/vortices of the middle layer (prototypes of intrathermocline vortices in the ocean) belonging to the middle layer of a three-layer rotating fluid. The lower layer is assumed to be dynamically passive. The piecewise constant vertical density distribution approximates the average long-term profile for the North Atlantic, where intrathermocline eddies are observed most often at depths of 300–1600 m. Numerical experiments were carried out with different initial configurations of vortices, to evaluate several effects. Firstly, the stability of the vortex compound was evaluated. Most often, it remains compact, but when unstable, it can break as vertically coupled vortex dipoles (called hetons). Secondly, we studied the interaction between a vertically tilted cyclone and lenses. Then, the lenses first undergo anticlockwise rotation determined by the surface cyclone. The lenses can induce alignment or coupling with cyclonic vorticity above them. Only very weak lenses are destroyed by the shear stress exerted by the surface cyclone. Thirdly, under the influence of lens dipoles, the surface cyclone can be torn apart. In particular, the shedding of rapidly moving vortex pairs at the surface reflects the presence of lens dipoles below. More slowly moving small eddies can also be torn away from the main surface cyclone. In this case, they do not appear to be coupled with middle layer vortices. They are the result of large shear-induced deformation. Common and differing features of the vortex interaction, modeled in the framework of the theory of point and finite-core vortices, are noted.
Highlights
Vortices are ubiquitous features of many fluid flows.They are often long living and they carry substantial energy or chemical tracers across the fluid.They are the key to the description of developed turbulence [1,2]
The most convenient and effective method to solve the equations for our problem is the contour dynamics method which assumes that the potential vorticity in each layer is zero, everywhere except for a finite set of areas in which it takes constant values
The various numerical experiments aim at Hereafter, we will the locations of the middle layer, or intrathermocline lenses (ITLs) and determining: dipole structures relative to the position of the upper layer cyclone
Summary
Vortices are ubiquitous features of many fluid flows (geophysical, industrial, biological flows). These theorems are central to vortex dynamics, a specific study of which follows They allow the full description of the flow by the potential vorticity distribution which is advected by the velocity field that it itself generates. These theorems arethe central to equations vortex dynamics, a specificmethod study of(Section which follows. The surface vortex be vortices, but thiswith model has been shown to satisfactorily interactions such will as the represented as a patch of uniform, positive, potential vorticity in the upper layer. Of vortices of the same sign belonging to one layer [16], the interaction of vortices located at different layers [22], and the effect of the bottom topography on the dynamics of intrathermocline lenses [20]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
