Jupiter's Cloud Structure from Galileo Imaging Data

Banfield, D.; Gierasch, P. J.; Bell, Maureen; Ustinov, E. A.; Ingersoll, Andrew P.; Vasavada, A. R.; West, Robert A.; Belton, M. J. S.

doi:10.1006/icar.1998.5985

Cited by 159 publications

(207 citation statements)

References 37 publications

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“…5-and 45-μm observations from Voyager IRIS were analysed by Gierasch et al (1986), who concluded that there was a highly variable cloud deck at ∼700 mbar, near the expected ammonia condensation level. Imaging data from the Galileo spacecraft showed evidence for thick, variable clouds in the 750±200 mbar region (Banfield et al, 1998), again consistent with NH 3 . Further support came in the form of spectroscopic identification of ammonia-ice features, using the 1-3 µm region of the Galileo NIMS spectra (Baines et al, 2002) and 9 µm data from Cassini CIRS (Wong et al, 2004).…”

Section: Introductionmentioning

confidence: 69%

“…Banfield et al (1998) used Galileo SSI observations to identify a deep cloud (located at a pressure greater than 4 bar) in one region close to the Great Red Spot, which they concluded was likely to be composed of water. Similarly, Simon-Miller et al (2000) found evidence for the cloud in very small regions of the planet by identifying a water ice feature near 44 µm in Voyager IRIS spectra.…”

Section: Introductionmentioning

confidence: 99%

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Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Giles

Fletcher

Irwin

2015

Icarus

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Jupiter's tropospheric composition and cloud structure are studied using Cassini VIMS 4.5-5.1 µm thermal emission spectra from the 2000-2001 flyby. We make use of both nadir and limb darkening observations on the planet's nightside, and compare these with dayside observations. Although there is significant spatial variability in the 5-μm brightness temperatures, the shape of the spectra remain very similar across the planet, suggesting the presence of a spectrally-flat, spatially inhomogeneous cloud deck. We find that a simple cloud model consisting of a single, compact cloud is able to reproduce both nightside and dayside spectra, subject to the following constraints: (i) the cloud base is located at pressures of 1.2 bar or lower; (ii) the cloud particles are highly scattering; (iii) the cloud is sufficiently spectrally flat. Using this cloud model, we search for global variability in the cloud opacity and the phosphine deep volume mixing ratio. We find that the vast majority of the 5-μm inhomogeneity can be accounted for by variations in the thickness of the cloud decks, with huge differences between the cloudy zones and the relatively cloud-free belts. The relatively low spectral resolution of VIMS limits reliable retrievals of gaseous species, but some evidence is found for an enhancement in the abundance of phosphine at high latitudes.

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Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Giles

Fletcher

Irwin

2015

Icarus

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“…For comparison with the optical depths of ours and West et alÏs (at a mid-visible wavelength of 0.55 km), we scale BanÐeld et alÏs q by the ratio of extinction efficiencies at 0.55 to 0.756 km for 0.2 km particles (using their refractive index of 1.4), resulting in a mid-visible q range of D2È10. Hence, the West et al (1986) and BanÐeld et al (1998) results are e †ectively identical and are hereafter lumped together as "" West et alÏÏ…”

Section: Comparisons With Observationsmentioning

confidence: 99%

“…More recently, BanÐeld et al (1998), who make no attempt to retrieve particle sizes, assume a particle e †ective radius of 0.2 km and retrieve optical depths from Galileo imaging data at a wavelength of 0.756 km that cluster in the range D1È4.5 (their Fig. 9).…”

Section: Comparisons With Observationsmentioning

confidence: 99%

Precipitating Condensation Clouds in Substellar Atmospheres

Ackerman

Marley

2001

ApJ

755

1,280

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We present a method to calculate vertical proÐles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent di †usion and sedimentation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with results from previous methods. An adjustable parameter describing the efficiency of sedimentation allows the new model to span the range of predictions made by previous models. Calculations for the Jovian ammonia cloud are consistent with observations. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet. We Ðnd that precipitating cloud decks naturally account for the characteristic trends seen in the spectra of Land T-type ultracool dwarfs.

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“…All the planets have clouds with the main cloud deck at about 0.75 bar in Jupiter (Banfield et al 1998; Kedziora-Chudczer & Bailey 2011), 2.5 bar in Saturn (Fletcher et al 2011) and ∼2 bar in Uranus and Neptune (Irwin, Teanby, & Davis 2010).…”

Section: Solar System Giant Planetsmentioning

confidence: 99%

The Dawes Review 3: The Atmospheres of Extrasolar Planets and Brown Dwarfs

Bailey

2014

Publ. Astron. Soc. Aust.

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The last few years has seen a dramatic increase in the number of exoplanets known and in the range of methods for characterising their atmospheric properties. At the same time, new discoveries of increasingly cooler brown dwarfs have pushed down their temperature range which now extends down to Y-dwarfs of < 300 K. Modelling of these atmospheres has required the development of new techniques to deal with the molecular chemistry and clouds in these objects. The atmospheres of brown dwarfs are relatively well understood, but some problems remain, in particular the behavior of clouds at the L/T transition. Observational data for exoplanet atmosphere characterisation is largely limited to giant exoplanets that are hot because they are near to their star (hot Jupiters) or because they are young and still cooling. For these planets there is good evidence for the presence of CO and H2O absorptions in the IR. Sodium absorption is observed in a number of objects. Reflected light measurements show that some giant exoplanets are very dark, indicating a cloud free atmosphere. However, there is also good evidence for clouds and haze in some other planets. It is also well established that some highly irradiated planets have inflated radii, though the mechanism for this inflation is not yet clear. Some other issues in the composition and structure of giant exoplanet atmospheres such as the occurrence of inverted temperature structures, the presence or absence of CO2and CH4, and the occurrence of high C/O ratios are still the subject of investigation and debate.

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Jupiter's Cloud Structure from Galileo Imaging Data

Cited by 159 publications

References 37 publications

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Precipitating Condensation Clouds in Substellar Atmospheres

The Dawes Review 3: The Atmospheres of Extrasolar Planets and Brown Dwarfs

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