Comparison of the Deep Atmospheric Dynamics of Jupiter and Saturn in Light of the Juno and Cassini Gravity Measurements

Kaspi, Yohai; Galanti, Eli; Showman, Adam P.; Stevenson, D. J.; Guillot, T.; Iess, L.; Bolton, S. J.

doi:10.1007/s11214-020-00705-7

Cited by 66 publications

(70 citation statements)

References 130 publications

(122 reference statements)

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“…2014 b ) and penetrate deep into the planet's interior (Kaspi et al. 2018, 2020). Apart from their strength, jets on gas giants are also puzzling by their stability since the pattern has barely varied over decades (Porco et al.…”

Section: Introductionmentioning

confidence: 99%

Zonal jets at the laboratory scale: hysteresis and Rossby waves resonance

2021

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Section: Introductionmentioning

confidence: 99%

Zonal jets at the laboratory scale: hysteresis and Rossby waves resonance

2021

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“…Previous work on constraining the deep flow structure was done using all four measured gravity harmonics combined (e.g., Kaspi et al, 2018Kaspi et al, , 2020Kong et al, 2018). However, an important question is how does each gravity harmonic individually constrain the flow strength at different depths.…”

Section: Introductionmentioning

confidence: 99%

The Range of Jupiter's Flow Structures That Fit the Juno Asymmetric Gravity Measurements

2020

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The asymmetric gravity field measured by the Juno spacecraft has allowed the estimation of the depth of Jupiter's zonal jets, showing that the winds extend approximately 3,000 km beneath the cloud level. This estimate was based on an analysis using a combination of all measured odd gravity harmonics, J3, J5, J7, and J9, but the wind profile's dependence on each of them separately has yet to be investigated. Furthermore, these calculations assumed the meridional profile of the cloud‐level wind extends to depth. However, it is possible that the interior jet profile varies somewhat from that of the cloud level. Here we analyze in detail the possible meridional and vertical structure of Jupiter's deep jet streams that can match the gravity measurements. We find that each odd gravity harmonic constrains the flow at a different depth, with J3 the most dominant at depths below 3,000 km, J5 the most restrictive overall, whereas J9 does not add any constraint on the flow if the other odd harmonics are considered. Interior flow profiles constructed from perturbations to the cloud‐level winds allow a more extensive range of vertical wind profiles, yet when the meridional profiles differ substantially from the cloud level, the ability to match the gravity data significantly diminishes. Overall, we find that while interior wind profiles that do not resemble the cloud level are possible, they are statistically unlikely. Finally, inspired by the Juno microwave radiometer measurements, assuming the brightness temperature is dominated by the ammonia abundance, we find that depth‐dependent flow profiles are still compatible with the gravity measurements.

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“…This difference was attributed to the winds extending thousands of kilometers deep (Galanti et al, 2019). For both planets, the gravity measurements indicate not only the overall depth of the winds but also that the same meridional profile of the zonal flows likely extends to these depths (Kaspi et al, 2020).…”

Section: Introductionmentioning

confidence: 93%

Synergized magnetic and gravity measurements probe the detailed structure of the gas giants' deep atmospheres

Galanti¹,

Kaspi²

2020

Preprint

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<p>The strong zonal flows observed at the cloud-level of the gas giants extend thousands of kilometers deep into the planetary interior, as indicated by the Juno and Cassini gravity measurements. However, the gravity measurements alone, which are by definition an integrative measure of mass, cannot constrain with high certainty the detailed vertical structure of the flow below the cloud-level. Here we show that taking into account the recent magnetic field measurements of Saturn and past secular variations of Jupiter's magnetic field, give an additional physical constraint on the vertical decay profile of the observed zonal flows in these planets. In Saturn, we find that the cloud-level winds extend into the planet with very little decay (barotropically) down to a depth of around 7,000 km, and then decay rapidly, so that within the next 1,000 km their value reduces to about 1% of that at the cloud-level. This optimal deep flow profile structure of Saturn matches simultaneously both the gravity field and the high-order latitudinal variations in the magnetic field discovered by the recent measurements. In the Jupiter case, using the recent findings indicating the flows in the planet semiconducting region are order centimeters per second, we show that with such a constraint, a flow structure similar to the Saturnian one is consistent with the Juno gravity measurements. Here the winds extend unaltered from the cloud-level to a depth of around 2,000 km and then decay rapidly within the next 600 km to values of around 1%. Thus, in both giant planets, we find that the observed winds&#160; extend unaltered (baroctropically) down to the semiconducting region, and then decay abruptly. While is it plausible that the interaction with the magnetic field in the semiconducting region is responsible for winds final decay, it is yet to be understood whether another mechanism is involved in the process, especially in the initial decay form the strong 10s meter per seconds winds.</p>

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Comparison of the Deep Atmospheric Dynamics of Jupiter and Saturn in Light of the Juno and Cassini Gravity Measurements

Cited by 66 publications

References 130 publications

Zonal jets at the laboratory scale: hysteresis and Rossby waves resonance

Zonal jets at the laboratory scale: hysteresis and Rossby waves resonance

The Range of Jupiter's Flow Structures That Fit the Juno Asymmetric Gravity Measurements

Synergized magnetic and gravity measurements probe the detailed structure of the gas giants' deep atmospheres

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