Vortex merger in surface quasi-geostrophy

Xavier Carton, Daniele Ciani, Jacques Verron, Jean Noel Reinaud, Mikhail Sokolovskiy

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The merger of two identical surface temperature vortices is studied in the surface quasi- geostrophic model. The motivation for this study is the observation of the merger of sub- mesoscale vortices in the ocean. Firstly, the interaction between two point vortices, in the absence or in the presence of an external deformation field, is investigated. The rotation rate of the vortices, their stationary positions and the stability of these positions are determined. Then, a numerical model provides the steady states of two finite-area, constant-temperature, vortices. Such states are less deformed than their counterparts in two-dimensional incom- pressible flows. Finally, numerical simulations of the nonlinear surface quasi-geostrophic equations are used to investigate the finite-time evolution of initially identical and sym- metric, constant temperature vortices. The critical merger distance is obtained and the deformation of the vortices before or after merger is determined. The addition of external deformation is shown to favor or to oppose merger depending on the orientation of the vor- tex pair with respect to the strain axes. An explanation for this observation is proposed. Conclusions are drawn towards an application of this study to oceanic vortices.
Original languageEnglish
Number of pages22
JournalGeophysical and Astrophysical Fluid Dynamics
Volume110
Issue number1
Early online date23 Dec 2015
DOIs
Publication statusPublished - 2016

Keywords

  • Surface quasi-geostrophy
  • Vortex merger
  • Steady states
  • Critical distance
  • Shear/strain flow
  • Numerical model

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