Evidence for Multiple Ferrel‐Like Cells on Jupiter

Duer, Keren; Gavriel, Nimrod; Galanti, Eli; Kaspi, Yohai; Fletcher, Leigh N.; Guillot, T.; Bolton, S. J.; Levin, S. M.; Atreya, S. K.; Grassi, D.; Ingersoll, Andrew P.; Li, Cheng; Li, Liming; Lunine, Jonathan I.; Orton, Glenn S.; Oyafuso, Fabiano; Waite, J. H.

doi:10.1029/2021gl095651

Cited by 28 publications

(30 citation statements)

References 70 publications

(168 reference statements)

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“…This picture is usually connected to deep-shell simulations of rotating convection (e.g., Aurnou & Olson 2001;Christensen 2001;Heimpel et al 2005;Kaspi et al 2009;Gastine & Wicht 2012;Yadav & Bloxham 2020). It is consistent with cloud tracking observations of the surface flows of Jupiter (e.g., Salyk et al 2006;Ingersoll et al 2021;Duer et al 2021), which show that the observed Reynolds stresses are consistent with a direct flux of angular momentum from the eddies into the jets. The corresponding upscale energy flux from the eddies to the jets is about three times stronger than the eddy-eddy upscale flux (Young & Read 2017) and thus supports the idea of primarily a direct driving.…”

Section: Direct Drivingsupporting

confidence: 90%

Direct driving of simulated planetary jets by upscale energy transfer

Böning

Wulff

Dietrich

et al. 2023

A&A

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Context. The precise mechanism that forms jets and large-scale vortices on the giant planets is unknown. An inverse cascade has been suggested by several studies. Alternatively, energy may be directly injected by small-scale convection. Aims. Our aim is to clarify whether an inverse cascade feeds zonal jets and large-scale eddies in a system of rapidly rotating, deep, geostrophic spherical-shell convection. Methods. We analyze the nonlinear scale-to-scale transfer of kinetic energy in such simulations as a function of the azimuthal wave number, m. Results. We find that the main driving of the jets is associated with upscale transfer directly from the small convective scales to the jets. This transfer is very nonlocal in spectral space, bypassing large-scale structures. The jet formation is thus not driven by an inverse cascade. Instead, it is due to a direct driving by Reynolds stresses, statistical correlations of velocity components of the small-scale convective flows. Initial correlations are caused by the effect of uniform background rotation and shell geometry on the flows and provide a seed for the jets. While the jet growth suppresses convection, it increases the correlation of the convective flows, which further amplifies the jet growth until it is balanced by viscous dissipation. To a much smaller extent, energy is transferred upscale to large-scale vortices directly from the convective scales, mostly outside the tangent cylinder. There, large-scale vortices are not driven by an inverse cascade either. Inside the tangent cylinder, the transfer to large-scale vortices is even weaker, but more local in spectral space, leaving open the possibility of an inverse cascade as a driver of large-scale vortices. In addition, large-scale vortices receive kinetic energy from the jets via forward transfer. We therefore suggest a jet instability as an alternative formation mechanism of largescale vortices. Finally, we find that the jet kinetic energy scales approximatively as −5 , the same as for the so-called zonostrophic regime.

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Section: Direct Drivingsupporting

confidence: 90%

Direct driving of simulated planetary jets by upscale energy transfer

Böning

Wulff

Dietrich

et al. 2023

A&A

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“…Predicting the structure and the dynamics of atmospheric circulation in Uranus and Neptune (both zonal and meridional) is crucial for understanding their heat transfer mechanisms (Podolak et al 2019;Vazan & Helled 2020;Hill et al 2021) and in turn their composition and vertical mixing of molecules (Nettelmann et al 2013;Fletcher 2021;Bailey & Stevenson 2021), generation of secondary magnetic fields via their interaction with zonal winds (Cao & Stevenson 2017;Soyuer & Helled 2021), and molecular advection phenomena (e.g., like those recently shown in Jupiter with ammonia; Duer et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Zonal Winds of Uranus and Neptune: Gravitational Harmonics, Dynamic Self-gravity, Shape, and Rotation

Soyuer

Neuenschwander

Helled

2022

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Uranus and Neptune exhibit fast surface zonal winds that can reach up to a few hundred meters per second. Previous studies on zonal gravitational harmonics and ohmic dissipation constraints suggest that the wind speeds diminish rapidly in relatively shallow depths within the planets. Through a case-by-case comparison between the missing dynamical gravitational harmonic J 4 ′ from structure models, and with that expected from fluid perturbations, we put constraints on zonal wind decay in Uranus and Neptune. To this end, we generate polytropic empirical structure models of Uranus and Neptune using fourth-order theory of figures that leave hydrostatic J 4 as an open parameter. Allotting the missing dynamical contribution to density perturbations caused by zonal winds (and their dynamic self-gravity), we find that the maximum scale height of zonal winds are ∼2%–3% of the planetary radii for both planets. Allowing the models to have J 2 solutions in the ±5 × 10−6 range around the observed value has similar implications. The effect of self-gravity on J 4 ′ is roughly a factor of ten lower than that of zonal winds, as expected. The decay scale heights are virtually insensitive to the proposed modifications to the bulk rotation periods of Uranus and Neptune in the literature. Additionally, we find that the dynamical density perturbations due to zonal winds have a measurable impact on the shape of the planet, and could potentially be used to infer wind decay and bulk rotation period via future observations.

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“…Work on the MWR results continues. Duer et al (2021) show evidence of downwelling below the zones from 1.5 to 240 bars, with 16 belt-zone pairs from −60 to 60 latitude. Fletcher et al (2021) documents an ammonia minimum near the 5-bar level, and Guillot et al (2020) explains how some ammonia might escape detection at that level.…”

mentioning

confidence: 95%

Jupiter's Overturning Circulation: Breaking Waves Take the Place of Solid Boundaries

Ingersoll

Atreya

Bolton

et al. 2021

Geophysical Research Letters

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Cloud‐tracked wind observations document the role of eddies in putting momentum into the zonal jets. Chemical tracers, lightning, clouds, and temperature anomalies document the rising and sinking in the belts and zones, but questions remain about what drives the flow between the belts and zones. We suggest an additional role for the eddies, which is to generate waves that propagate both up and down from the cloud layer. When the waves break they deposit momentum and thereby replace the friction forces at solid boundaries that enable overturning circulations on terrestrial planets. By depositing momentum of one sign within the cloud layer and momentum of the opposite sign above and below the clouds, the eddies maintain all components of the circulation, including the stacked, oppositely rotating cells between each belt‐zone pair, and the zonal jets themselves.

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Evidence for Multiple Ferrel‐Like Cells on Jupiter

Abstract: Over the last few decades, spacecraft and ground-based observations have gathered data about Jupiter's atmosphere, including measurements of cloud reflectance (

Cited by 28 publications

References 70 publications

Direct driving of simulated planetary jets by upscale energy transfer

Direct driving of simulated planetary jets by upscale energy transfer

Zonal Winds of Uranus and Neptune: Gravitational Harmonics, Dynamic Self-gravity, Shape, and Rotation

Jupiter's Overturning Circulation: Breaking Waves Take the Place of Solid Boundaries

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