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Stable 3-Dimensional Vortex Families Consistent with Jovian Observations Including the Great Red Spot

Presentation #508.06D in the session Origin and Evolution of Giant Planet Systems II (Oral Presentation)

Published onOct 23, 2023
Stable 3-Dimensional Vortex Families Consistent with Jovian Observations Including the Great Red Spot

We compute the 3-dimensional structures of families of long-lived planetary anticyclones that thrive in the observed hydrostatic thermal structure and zonal winds of the Jovian atmosphere. Detailed observations of the horizontal velocities of Jovian vortices exist at only one height in the atmosphere – the visible cloud top level – and we have compared the velocities of our stable numerical solutions to those observations. However, because there are no quantitative observations of the Jovian velocities at other heights, the vertical structures of the vortices are poorly understood. We solve the 3-dimensional anelastic equations with a high-resolution pseudo-spectral method. We examine several families of vortices. We find that the family (we call CV) of anticyclones with approximately constant vorticity as a function of height and with horizontal areas that go to zero at their tops and bottoms are stable to large perturbations and, depending on their sizes, look either like the Great Red Spot (GRS) or like the Red Oval and former White Ovals. In contrast, the family (we call CA) of anticyclones with approximately constant horizontal area as a function of height and with vorticity that goes to zero at their tops and bottoms are unstable. When our numerical code is initialized with a CA vortex it goes unstable and reforms as a CV vortex. Our final, stable vortices show other unexpected properties. Vortices that are initially non-hollow become hollow (i.e., have local minima of vertical vorticity at their center), which is a feature of the GRS that cannot be explained with 2-dimensional simulations. Another surprising result is that although an initial vortex has uniform potential temperature at the height of the visible clouds, it spontaneously evolves so that an annulus near its outer edge becomes 1-2 K warmer. This is consistent with the observations of the bright 5-micron IR rings around Jovian anticyclones, We analytically prove that the horizontal mid-plane of a stable vortex must lie at a height above the top of the convective zone.

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