On the Saturation and Temporal Variation of Mean Zonal Flows: An Implication for Equatorial Jets on Giant Planets

Liao, Xinhao; Feng, Tao; Zhang, Keke

doi:10.1086/521526

Cited by 2 publications

(2 citation statements)

References 23 publications

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“…Potential vorticity conservation causes convection columns in the equatorial region to become tilted in the prograde azimuthal direction as they travel outward in cylindrical radius. The prograde tilt of these columnar plumes generates non‐linear Reynolds stresses that drive large‐scale axially invariant zonal flows (Zhang 1992; Liao et al 2007). Thus, kinetic energy of turbulent cylindrically radial motions, u ′ s , is converted into kinetic energy of zonal motions.…”

Section: Discussionmentioning

confidence: 99%

Convective heat transfer and the pattern of thermal emission on the gas giants

Aurnou¹,

Heimpel

Allen

et al. 2008

Geophysical Journal International

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S U M M A R YJupiter and Saturn emit nearly twice the thermal energy they receive from the Sun. Although insolation decreases toward the poles, the large-scale outward heat flux is nearly uniform, with smaller-scale latitudinal undulations that correlate with the zonal jet streams. Here we present numerical models of rapidly rotating, turbulent 3-D convection in geometrically thin, uniformly forced layers of Boussinesq fluid that approximate the deep convection zones of Jupiter and Saturn. In previous studies we have demonstrated that such models generate zonal flows comparable to those observed on the gas giants. By analysing the simulated patterns of convective heat transfer, we show here that deep convection in the gas giants can explain the anomalously uniform large-scale thermal emissions as well as the jet-scale variations. In particular, we find that convective heat transfer by quasi-geostrophic thermal plumes in relatively thin spherical shell geometry generates an outward heat flow pattern with a broad equatorial minimum and peaks at the poles. The results suggest an alternative to the hypothesis that insolation controls the large-scale patterns of heat flux and zonal flow on the gas giants. Instead, we propose that the large-scale thermal and zonal flow fields originate deep within the planets' molecular envelopes.

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Section: Discussionmentioning

confidence: 99%

Convective heat transfer and the pattern of thermal emission on the gas giants

Aurnou¹,

Heimpel

Allen

et al. 2008

Geophysical Journal International

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“…That does not mean the flow is unstable, however, as there are other stability criteria that involve vertical structure ( Dowling 1995 ). Liao et al (2007) argue that a statistical equilibrium occurs as the growing wave saturates. In their global vortex analysis, Trammell et al (2014) find a correlation between the number of vortices and the westward jet peaks, implying at least some degree of instability at those latitudes.…”

Section: Vortices Mean Flow and Eddiesmentioning

confidence: 99%

Cassini Exploration of the Planet Saturn: A Comprehensive Review

Ingersoll

2020

Space Sci Rev

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Before Cassini, scientists viewed Saturn’s unique features only from Earth and from three spacecraft flying by. During more than a decade orbiting the gas giant, Cassini studied the planet from its interior to the top of the atmosphere. It observed the changing seasons, provided up-close observations of Saturn’s exotic storms and jet streams, and heard Saturn’s lightning, which cannot be detected from Earth. During the Grand Finale orbits, it dove through the gap between the planet and its rings and gathered valuable data on Saturn’s interior structure and rotation. Key discoveries and events include: watching the eruption of a planet-encircling storm, which is a 20- or 30-year event, detection of gravity perturbations from winds 9000 km below the tops of the clouds, demonstration that eddies are supplying energy to the zonal jets, which are remarkably steady over the 25-year interval since the Voyager encounters, re-discovery of the north polar hexagon after 25 years, determination of elemental abundance ratios He/H, C/H, N/H, P/H, and As/H, which are clues to planet formation and evolution, characterization of the semiannual oscillation of the equatorial stratosphere, documentation of the mysteriously high temperatures of the thermosphere outside the auroral zone, and seeing the strange intermittency of lightning, which typically ceases to exist on the planet between outbursts every 1–2 years. These results and results from the Jupiter flyby are all discussed in this review.

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On the Saturation and Temporal Variation of Mean Zonal Flows: An Implication for Equatorial Jets on Giant Planets

Cited by 2 publications

References 23 publications

Convective heat transfer and the pattern of thermal emission on the gas giants

Convective heat transfer and the pattern of thermal emission on the gas giants

Cassini Exploration of the Planet Saturn: A Comprehensive Review

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