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Quasi-geostrophic vortex solutions over isolated topography

Published online by Cambridge University Press:  17 March 2021

Jeasson F. Gonzalez Open the ORCID record for Jeasson F. Gonzalez [Opens in a new window]  and
L. Zavala Sansón Open the ORCID record for L. Zavala Sansón [Opens in a new window]
Jeasson F. Gonzalez
Affiliation:
Department of Physical Oceanography, CICESE, Ensenada 22860, Mexico
L. Zavala Sansón*
Affiliation:
Department of Physical Oceanography, CICESE, Ensenada 22860, Mexico
*
†Email address for correspondence: lzavala@cicese.mx
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Abstract

Analytical solutions of barotropic, quasi-geostrophic vortices over an axisymmetric bottom topography are presented. The solutions are based on independent azimuthal modes adapted to the shape of the topography. Modes 0 (circular monopoles) and 1 (asymmetric dipoles) are evaluated for different topographic profiles that represent either submarine mountains or valleys. The interior fields are matched with an exterior flow with streamlines enclosing the vortices, so the structures remain trapped over the topographic feature. The solutions are steady in a reference frame attached to the rotation of the vortices around the topography. The main features of trapped vortices as a function of the topographic parameters, such as the structure, strength and angular speed, are discussed through numerical simulations initialised with theoretical vorticity fields. The model results reproduce reasonably well the analytical solutions when the topographic effects are strong enough to inhibit the dipole self-propagation. In contrast, very intense dipolar modes may escape from the influence of the topography.

JFM classification

Geophysical and Geological Flows: Quasi-geostrophic flows Geophysical and Geological Flows: Topographic effects Geophysical and Geological Flows: Rotating flows
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 915 , 25 May 2021 , A64
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Copyright
© The Author(s), 2021. Published by Cambridge University Press

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References

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Gonzalez and Zavala Sansón supplementary movie 1

Evolution of the relative vorticity of a dipolar vortex on the f-plane over an abrupt mountain (flow parameters in Figure 4a).

Download Gonzalez and Zavala Sansón supplementary movie 1(Video)
Video 614.7 KB

Gonzalez and Zavala Sansón supplementary movie 2

Evolution of the relative vorticity of a dipolar vortex on the f-plane over an abrupt valley (flow parameters in Figure 4c).

Download Gonzalez and Zavala Sansón supplementary movie 2(Video)
Video 719.4 KB