Storms and the Depletion of Ammonia in Jupiter: II. Explaining the Juno observations

Guillot, T.; Li, Cheng; Bolton, S. J.; Brown, Shannon; Ingersoll, Andrew P.; Janssen, M. A.; Levin, S. M.; Lunine, Jonathan I.; Orton, Glenn S.; Steffes, Paul G.; Stevenson, D. J.

doi:10.1002/essoar.10502179.1

Cited by 2 publications

(2 citation statements)

References 42 publications

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“…Ammonia is not uniformly distributed in Jupiter’s atmosphere below the clouds, but depleted to around 30 bar at all latitudes except at the equator [13]. A viable model to explain this global desiccation is that water-powered moist convective storms could trap ammonia in hailstones that would precipitate and deplete the upper atmosphere of ammonia [25,26], making water-powered moist convective storms an essential piece of the jovian meteorology. This mechanism is in agreement with the ammonia and lower clouds aerosol depletion observed in Saturn after the development of the large Great White Storm of 2010–2011 [22–24] and could be a general drying mechanism affecting also the atmospheres of Uranus and Neptune in case moist convection from a lower cloud could reach the condensation region of a volatile of the upper atmosphere.…”

Section: A Complex Weather Layermentioning

confidence: 99%

“…Recent observations of Jupiter’s deep weather layer by Juno [13] and the very large array (VLA) [20,21], and results from Cassini following the 2010–2011 Great Storm in Saturn [22–24] suggest that moist convection acts in both planets to desiccate NH 3 of the upper trospospheres below the ammonia condensation level due to details in the thermodynamics of the water ammonia system [25,26]. But do other volatiles transport mechanisms occur in Uranus and Neptune cloud layers?…”

Section: Introductionmentioning

confidence: 99%

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Convective storms and atmospheric vertical structure in Uranus and Neptune

Hueso

Guillot

Sánchez‐Lavega

2020

Phil. Trans. R. Soc. A.

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The ice giants Uranus and Neptune have hydrogen-based atmospheres with several constituents that condense in their cold upper atmospheres. A small number of bright cloud systems observed in both planets are good candidates for moist convective storms, but their observed properties (size, temporal scales and cycles of activity) differ from moist convective storms in the gas giants. These clouds and storms are possibly due to methane condensation and observations also suggest deeper clouds of hydrogen sulfide (H 2 S) at depths of a few bars. Even deeper, thermochemical models predict clouds of ammonia hydrosulfide (NH 4 SH) and water at pressures of tens to hundreds of bars, forming extended deep weather layers. Because of hydrogen’s low molecular weight and the high abundance of volatiles, their condensation imposes a strongly stabilizing vertical gradient of molecular weight larger than the equivalent one in Jupiter and Saturn. The resulting inhibition of vertical motions should lead to a moist convective regime that differs significantly from the one occurring on nitrogen-based atmospheres like those of Earth or Titan. As a consequence, the thermal structure of the deep atmospheres of Uranus and Neptune is not well understood. Similar processes might occur at the deep water cloud of Jupiter in Saturn, but the ice giants offer the possibility to study these physical aspects in the upper methane cloud layer. A combination of orbital and in situ data will be required to understand convection and its role in atmospheric dynamics in the ice giants, and by extension, in hydrogen atmospheres including Jupiter, Saturn and giant exoplanets. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

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Section: A Complex Weather Layermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Convective storms and atmospheric vertical structure in Uranus and Neptune

Hueso

Guillot

Sánchez‐Lavega

2020

Phil. Trans. R. Soc. A.

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The turbulent dynamics of Jupiter’s and Saturn’s weather layers: order out of chaos?

2020

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The weather layers of the gas giant planets, Jupiter and Saturn, comprise the shallow atmospheric layers that are influenced energetically by a combination of incoming solar radiation and localised latent heating of condensates, as well as by upwelling heat from their planetary interiors. They are also the most accessible regions of those planets to direct observations. Recent analyses in Oxford of cloud-tracked winds on Jupiter have demonstrated that kinetic energy is injected into the weather layer at scales comparable to the Rossby radius of deformation and cascades both upscale, mostly into the extra-tropical zonal jets, and downscale to the smallest resolvable scales in Cassini images. The large-scale flow on both Jupiter and Saturn appears to equilibrate towards a state which is close to marginal instability according to Arnol’d’s 2nd stability theorem. This scenario is largely reproduced in a hierarchy of numerical models of giant planet weather layers, including relatively realistic models which seek to predict thermal and dynamical structures using a full set of parameterisations of radiative transfer, interior heat sources and even moist convection. Such models include (amongst others) the Jason GCM, developed in Oxford, which also represents the formation of (energetically passive) clouds of NH3, NH4SH and H2O condensates and the transport of condensable tracers. Recent results show some promise in comparison with observations from the Cassini and Juno missions, but some observed features (such as Jupiter’s Great Red Spot and other compact ovals) are not yet captured spontaneously by most weather layer models. We review recent work in this vein and discuss a number of open questions for future study.

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Storms and the Depletion of Ammonia in Jupiter: II. Explaining the Juno observations

Cited by 2 publications

References 42 publications

Convective storms and atmospheric vertical structure in Uranus and Neptune

Convective storms and atmospheric vertical structure in Uranus and Neptune

The turbulent dynamics of Jupiter’s and Saturn’s weather layers: order out of chaos?

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