Oscillations and Stability of the Jupiter Polar Cyclones

Mura, A.; Adriani, A.; Plainaki, C.; Moriconi, M. L.; Grassi, D.; Ingersoll, Andrew P.; Bolton, S. J.; Sordini, R.; Altieri, F.; Ciarravano, Alessandro; Cicchetti, A.; Dinelli, B. M.; Filacchione, G.; Migliorini, A.; Noschese, R.; Piccioni, G.; Scarica, P.; Sindoni, G.; Stefani, S.; Tosi, F.; Turrini, D.

doi:10.1029/2021gl094235

Cited by 12 publications

(44 citation statements)

References 27 publications

(59 reference statements)

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“…A finite deformation radius

complicates our model because the conversion between kinetic and potential energies resulting from finite

implies that the initial root-mean-square velocity, U defined in [ 5 ], is not constant during the evolution. We take comfort in recent observations and numerical results ( 3 , 14 , 39 , 40 ) indicating that polar cyclones might have a strong barotropic component.…”

Section: Discussionsupporting

confidence: 80%

“…Once the permanent central cyclone is established, the octet crystallizes into solid-body rotation ( Movie S3 ). The solid-body rotation is not perfect: Vortices have small epicyclic oscillations about their mean position, reminiscent of the oscillations of the cyclones about their mean position at the South Pole of Jupiter ( 3 , 4 ). The oscillations may result from differences in strength between the eight cyclones; e.g., the smallest cyclones have the largest excursions.…”

Section: Results: the Polar Capmentioning

confidence: 99%

“…These cyclones are organized into a vortex crystal: a symmetric array of strong vortices in solid-body rotation within a background of weaker vorticity. The Jovian vortex crystals are located within 8

of the poles and have endured since their discovery in 2016 with very little change to their overall structure ( 2 , 3 ). Jovian crystals are approximately stationary in the System III reference frame ( 4 ).…”

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confidence: 99%

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Polar vortex crystals: Emergence and structure

Siegelman

Young

Ingersoll

2022

Proc. Natl. Acad. Sci. U.S.A.

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Significance Vortex crystals, geometric arrays of like-signed vortices, are observed in natural systems with vastly different space and time scales: at the poles of Jupiter (∼10,000-km radius and lifetime of at least 5 y) and in laboratory experiments with pure-electron plasma (∼3.5-cm radius, lifetime of about 1.7 s). We follow the adage “less is more” and show that minimal physics is required for polar vortex crystals formation and persistence. Crystals, resembling those of Jupiter, form from the free evolution of an unstratified and rapidly rotating fluid in an axisymmetric geometry. An essential ingredient in this minimal model is the decrease of the vertical component of the Coriolis force with distance from the pole. Once formed, the crystal seems to survive indefinitely.

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“…A finite deformation radius

complicates our model because the conversion between kinetic and potential energies resulting from finite

Section: Discussionsupporting

confidence: 80%

Section: Results: the Polar Capmentioning

confidence: 99%

mentioning

confidence: 99%

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Polar vortex crystals: Emergence and structure

Siegelman

Young

Ingersoll

2022

Proc. Natl. Acad. Sci. U.S.A.

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“…The locations of the CPCs have been monitored since Juno's arrival at Jupiter (Adriani et al., 2020; Mura et al., 2021; Tabataba‐Vakili et al., 2020). While the average locations of the cyclones match the calculations of Gavriel and Kaspi (2021) (hereafter GK21), the individual cyclones were found to oscillate around these stable positions, where perturbations seem to pass on between neighboring cyclones (Mura et al., 2021). In addition, an average westward drift of approximately 7.5° (3°) per year was measured on the cyclones at the south (north) pole (Adriani et al., 2020; Mura et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

The Oscillatory Motion of Jupiter's Polar Cyclones Results From Vorticity Dynamics

Gavriel

Kaspi

2022

Geophysical Research Letters

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The poles of Jupiter were observed in detail for the first time by the Juno spacecraft in 2016 (Bolton et al., 2017). In contrast with the polar regions of Saturn, which are inhabited by a single polar cyclone (PC) (Baines et al., 2009;Sánchez-Lavega et al., 2006), Jupiter's PCs are surrounded by a ring of stable circumpolar cyclones (CPCs) (Adriani et al., 2018;Orton et al., 2017). There are eight CPCs at the north pole and five at the south (Figure 1), each with a diameter of roughly 5,000 km and velocities reaching 100 ms −1 (Adriani et al., 2020;Grassi et al., 2018). Such cyclones can be generated by moist convection (O'Neill et al., 2015(O'Neill et al., , 2016, where 2D inverse energy cascade in the turbulent polar regions brings the kinetic energy from the convective scale up to the horizontal scale of the cyclones (Moriconi et al., 2020;. These regions are bounded by prograde jets at around latitudes 65°N∖S (Rogers et al., 2017(Rogers et al., , 2022, which may act as a separating barrier. In contrast with the Great Red Spot, which is centered around latitude 20°S and has a shallow depth (less than 500 km, Parisi et al. ( 2021)) relative to the deep surrounding jets (∼3,000 km, Kaspi et al. ( 2018)), the polar cyclones, subject to the Taylor-Proudman theorem (Vallis, 2017) with a vertical axis parallel to the planetary rotation axis and a smaller Rossby number, potentially extend deeper, suggesting a 2D dynamical regime.The beta-drift is a force that results from a dipole of vorticity (usually termed "beta-gyres," Sutyrin and Flierl (1994)) that is induced by an interaction between the tangential velocity of a cyclone and a gradient of potential vorticity (PV) that is present in the background of the cyclone (Chan, 2005;Gavriel & Kaspi, 2021;Rossby, 1948). This force creates a poleward drift on cyclones and an equatorward drift on anticyclones when only the planetary vorticity gradient (β) is considered (Chan, 2005;Franklin et al., 1996;Merlis & Held, 2019). Beta-drift is a known contributor to the poleward motion of Earth's tropical cyclones (Zhao et al., 2009), and was shown in shallow-water (SW) models to result in cyclones merging into a PC in settings characterizing gas-giants such as Jupiter and Saturn (

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“…The general structure of the polar cyclones is maintained along the PJ passages: the pentagon of circumpolar cyclones is always present, although the entire structure rotated from PJ 4 until the more recent orbits of Juno spacecraft (Mura et al, 2021) and the angular distance between CPC 1 and CPC 5 widened during PJ 33.…”

Section: Accepted Articlementioning

confidence: 99%