A laboratory model for Jovian polar vortex crystals

Abstract

We present an experimental model in which three similar cyclonic vortices are released into the upper layer of a rotating, two-layer stratified fluid system with a free upper surface, and spontaneously organize into a stable, long-lived vortex crystal. We analyze the crystal organization using a simplified toy model, in which the radial dynamics arise from a balance between an attractive force (the β-effect) and repulsive interactions between neighboring vortices. The experimental equilibrium distance agrees with the toy-model predictions. It increases with lower cyclone shielding, a greater number of vortices, and the presence of a central vortex. The azimuthal drift of the vortex crystals strongly correlates with their radial spacing: when far apart, they drift westward due to the β-drift, as seen at Jupiter’s poles; when close, strong mutual advection leads to eastward drift.