Vortices in sinusoidal shear, with applications to Jupiter

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Vilasur Swaminathan, Rohith
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In this thesis, we have studied the existence of vortex steady states in a sinusoidal background shear flow in a 1.75 layer quasi-geostrophic model. Trying to find vortex structures by integrating the Hamiltonian system has the drawback that the vortices lose enstrophy by filamentation and numerical dissipation, while continuing to deform and wobble. Adopting the local optimization technique of Hamiltonian Dirac Simulated Annealing overcomes this drawback and allows us to obtain steady/quasisteady vortices that have roughly the same area as that of the initial vortex. The steady states that we have generated range from elliptical with major axis aligned with the flow in the prograde shear region to triangular at the latitude where prograde and adverse shear meet and back to elliptical but with the major axis aligned perpendicular to the shear flow at the center of the adverse shear region. The steady states calculated by the above technique can be used for further analysis and as an initial condition to study the merger of vortices in background shear. This result is directly applicable to the kind of dynamics visible on planets like Jupiter, where vortices residing in zonal shear are a common occurrence.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2016
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Vilasur Swaminathan, R. (2016). Vortices in sinusoidal shear, with applications to Jupiter [Doctoral thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution]. Woods Hole Open Access Server. https://doi.org/10.1575/1912/7886
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