Formation of small-scale vortices in the core of a large merged vortex
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The merger of two surface quasi-geostrophic vortices is examined in detail. As the two vortices collapse towards each other in the merging process, they trap their external fronts between them; these fronts are inserted into the final merged vortex, where they form a central, nearly parallel, sheared velocity strip, sensitive to barotropic instability. As a result, this strip breaks up into an alley of small vortices. Subsequently, these small vortices may undergo merger and grow in size in the core of the large merged vortex. The number of small trapped vortices decreases correspondingly. Finally, a single or two small vortices remain. These processes are analysed using a numerical model of the surface quasi-geostrophic equations. The sensitivity of this process to the initial vortex characteristics is explored. A parallel is drawn between this problem and the instability of a rectilinear strip of temperature with a central gap. The application of this problem to the Ocean is discussed.
Oulhen , E , Reinaud , J N & Carton , X 2022 , ' Formation of small-scale vortices in the core of a large merged vortex ' , Geophysical and Astrophysical Fluid Dynamics , vol. 116 , no. 5-6 , pp. 411-432 . https://doi.org/10.1080/03091929.2022.2074983
Geophysical and Astrophysical Fluid Dynamics
Copyright © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
DescriptionFunding: We thank LOPS and UBO for a M.Sc internship grant which allowed the first author to carry out this work.
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