The interaction of two asymmetric quasi-geostrophic vortex patches
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Herein we study the general interaction of two vortex patches in a single-layer quasi-geostrophic shallow-water flow. Steadily-rotating equilibrium states are found over a wide parameter space spanning the Rossby deformation length, vortex area ratio, potential vorticity ratio, and gap between their innermost edges. A linear stability analysis is then used to identify the critical gap separating stable and unstable solutions, over the entire range of area and potential vorticity ratios, and for selected values of the Rossby deformation length. A representative set of marginally unstable equilibrium states are then slightly perturbed and evolved by an accurate contour dynamics numerical algorithm to understand the long-term fate of the instabilities. Not all instabilities lead to vortex merger; many in fact are characterised by weak filamentation and a small adjustment of the vortex shapes, without merger. Stronger instabilities lead to material being torn from one vortex and either wrapped around the other or reduced to ever thinning filamentary debris. A portion of the vortex may survive, or it may be completely strained out by the other.
Jalali , M M & Dritschel , D G 2018 , ' The interaction of two asymmetric quasi-geostrophic vortex patches ' , Geophysical and Astrophysical Fluid Dynamics , vol. Latest Articles . https://doi.org/10.1080/03091929.2018.1532508
Geophysical and Astrophysical Fluid Dynamics
Copyright © 2018 Informa UK Limited, trading as Taylor & Francis Group. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1080/03091929.2018.1532508
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