The Transition of a Stable Vortex from Hollow to Non-Hollow to Unstable - such as Jupiter's Great Red Spot

A hollow 3D vortex is one in which the absolute vertical vorticity has a local minimum at its center. Hollow vortices have never been seen in the lab, but hollow anticyclones exist in stratified, rotating astrophysical flows such as numerically-computed zombie vortices in protoplanetary disks and Jupiter’s Great Red Spot. The physics of vortex hollowness are not fully understood, but recent numerical simulations provide clues, and it may be that only anticyclones, rather than cyclones, can be hollow and that the hollowness is due to the fact that the fluid near the mid-plane of an anticyclone is always less stratified than its surrounding fluid. Simulations show that stable hollow vortices transition to stable unhollow vortices if the vortex becomes too vertically thin or too thick. If the resulting non-hollow vortex continues to have its thinness or thickness increased, the vortex becomes convectively unstable. In addition, if the ambient flow around a stable hollow vortex becomes sufficiently destratified, the vortex becomes un-hollow, and if it is further destratified, the vortex becomes unstable. A model based on hydrostatic equilibrium and geostrophic balance explains these observations and may allow us to find a prescription for creating stable hollow vortices in the lab. The model also explains many of the recent observations of Jupiter's Great Red Spot by the Hubble Space Telescope, James Webb Space Telescope, and Juno satellite.