Playing pool on the beta-plane: how weak initial perturbations predetermine the long-term evolution of coherent vortices
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Authors
Radko, Timour
Subjects
vortex dynamics
Advisors
Date of Issue
2021-02-04
Date
February 4, 2021
Publisher
Cambridge University Press
Language
Abstract
This study explores the long-term impact of a weak initial departure from circular
symmetry in coherent equivalent-barotropic vortices on their dynamics and evolution.
An algorithm is developed which makes it possible to construct models of vortices
that initially propagate with prescribed velocity. These solutions are used as the initial
conditions for a series of numerical simulations. Simulations indicate that seemingly minor
perturbations of dipolar form can control the propagation of vortices for extended periods,
during which they translate over distances greatly exceeding their size. The numerical
results are contrasted with the linear model, which assumes that the non-axisymmetric
component of circulation in the vortex interior is relatively weak. The linear solutions
reflect the self-propagation tendencies of coherent vortices to a much lesser degree, which
underscores the role of fundamentally nonlinear mechanisms at play. The remarkable
ability of quasi-monopolar vortices to retain the memory of weak initial perturbations
helps to rationalize the wide range of the observed propagation velocities of coherent
long-lived vortices in the ocean.
Type
Article
Description
17 USC 105 interim-entered record; under review.
The article of record as published may be found at https://doi.org/10.1017/jfm.2021.129
The article of record as published may be found at https://doi.org/10.1017/jfm.2021.129
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
National Science Foundation
Funder
OCE 1828843
Format
25 p.
Citation
Radko, Timour. "Playing pool on the beta-plane: how weak initial perturbations predetermine the long-term evolution of coherent vortices." Journal of Fluid Mechanics 915 (2021).
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.