Numerical Study of Stable Planetary Three-dimensional Vortices with a Hollow Vorticity Core

The Great Red Spot (GRS) is the largest and most long-lived planetary vortex, and it differs from other planetary, ocean, and laboratory vortices because it has a hollow vortex core. Its center has almost no vorticity. The physical explanation for this hollowness is unknown. In 2D shallow-water and quasigeostrophic initial-value calculations, an initially hollow vortex rapidly becomes unstable and either falls apart or reorganizes to become non-hollow. We present the first 3D numerical study of stable hollow vortices. The study uses a high-resolution, anelastic, initial-value code. When this code is initialized with non-hollow vortices, they evolve into stable hollow vortices. We discuss the importance of hollowness and how it relates to vortex dynamics and observations. We show how 3D effects (i.e., vertical motion as part of a secondary meridional circulation) can induce and maintain the hollow core of the vortex. One of our simulated stable hollow vortices has a horizontal velocity and vertical vorticity field that closely match the GRS.