The number and location of Jupiter’s circumpolar cyclones explained by vorticity dynamics

Abstract

The Juno mission observed that both poles of Jupiter have polar cyclones that are surrounded by a ring of circumpolar cyclones. The North Pole holds eight circumpolar cyclones and the South Pole possesses five, with both circumpolar rings positioned along latitude ∼ 84 • N/S. Here we explain the location, stability, and number of the Jovian circumpolar cyclones by establishing the primary forces that act on them, which develop because of vorticity gradients in the background of a cyclone. In the meridional direction, the background vorticity varies owning to the planetary sphericity and the presence of the polar cyclone. In the zonal direction, the vorticity varies by the presence of adjacent cyclones in the ring. Our analysis successfully predicts the latitude and number of circumpolar cyclones for both poles, according to the size and spin of the respective polar cyclone. Moreover, the analysis successfully predicts that Jupiter can hold circumpolar cyclones while Saturn currently cannot. The match between the theory and observations implies that vortices in the polar regions of the giant planets are largely governed by barotropic dynamics, and that the movement of other vortices at high-latitudes is also driven by interaction with the background vorticity.

Polar vortex crystals: Emergence and structure

“…3 C .) Slow algebraic decay, , differs qualitatively from the exponential decay of u assumed in recent models: Those models employ completely shielded vortices with ( 12 , 13 ).…”

“…Recent discussions ( 12 , 13 ) of the stability and structure of polar cyclones model the crystal using shielded vortices; e.g., azimuthal velocity decreases exponentially with distance from the vortex center (much faster than ). These authors emphasize the role of a shielded central polar cyclone and the planetary PV, , in forming a circumpolar PV ridge, i.e., a local radial maximum in PV.…”

“…Nonetheless many authors have remarked on the striking resemblance between electron-plasma vortex crystals and Jovian observations ( 1 , 4 , 12 , 13 ). While these two systems have many features in common, it is crucial to relax simplifications 1 and 2 in any model of polar atmospheres.…”

Dynamical Regimes of Polar Vortices on Terrestrial Planets with a Seasonal Cycle

“…Polar vortices are a ubiquitous feature of planetary atmospheres, with Earth, Venus, Mars, Titan, Jupiter, Saturn, and possibly Neptune and Pluto all exhibiting polar vortices (e.g., French & Gierasch 1979;Dyudina et al 2008;Teanby et al 2008;Polvani et al 2010;Luz et al 2011;Mitchell et al 2015;Adriani et al 2018;Gavriel & Kaspi 2021;Mitchell et al 2021). These polar vortices are a fundamental aspect of the atmospheric circulation and can be the site of unique microphysical and chemical processes, e.g., ozone depletion in Earth's stratosphere, CO 2 condensation on Mars, and HCN clouds on Titan.…”

Dynamical regimes of polar vortices on terrestrial planets with a seasonal cycle

“…Polar vortices are a ubiquitous feature of planetary atmospheres, with Earth, Venus, Mars, Titan, Jupiter, Saturn, and possibly Neptune and Pluto all exhibiting polar vortices (e.g., French & Gierasch 1979;Teanby et al 2008;Dyudina et al 2008;Luz et al 2011;Polvani et al 2010;Mitchell et al 2015;Adriani et al 2018;Gavriel & Kaspi 2021;Mitchell et al 2021). These polar vortices are a fundamental aspect of the atmo-spheric circulation, and can be the site of unique microphysical and chemical processes, e.g., ozone depletion in Earth's stratosphere, CO 2 condensation on Mars, and HCN clouds on Titan.…”