Models for Polar Haze Formation in Jupiter's Stratosphere

Friedson, A. J.; Wong, Anthony T.; Yung, Yuk L.

doi:10.1006/icar.2002.6885

Cited by 77 publications

(62 citation statements)

References 44 publications

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“…Calculations of the single scattering matrix and other optical properties of these particles were performed using the T-matrix theory combined with the superposition theorem (Mackowski & Mishchenko 2011), at λ = 0.55, 0.75 and 0.95 μm, and adopting a refractive index of 1.5 + i0.001, which corresponds to that of benzene (suggested to exist on the jovian poles by e.g. Friedson et al 2002). In Fig.…”

Section: Polar Haze Particlesmentioning

confidence: 99%

Flux and polarization signals of spatially inhomogeneous gaseous exoplanets

Karalidi

Stam

Guirado

2013

A&A

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Aims. We present numerically calculated, disk-integrated, spectropolarimetric signals of starlight that is reflected by vertically and horizontally inhomogeneous gaseous exoplanets. We include various spatial features that are present on Solar System's gaseous planets: belts and zones, cyclonic spots, and polar hazes, to test whether such features leave traces in the disk-integrated fux and polarization signals. Methods. Broadband flux and polarization signals of starlight that is reflected by gaseous exoplanets are calculated using an efficient, adding-doubling radiative transfer code, that fully includes single and multiple scattering and polarization. The planetary model atmospheres are vertically inhomogeneous and can be horizontally inhomogeneous, and contain gas molecules and/or cloud and/or aerosol particles.Results. The broadband flux and polarization signals are sensitive to cloud top pressures, although in the presence of local pressure differences, such as in belts and clouds, the flux and polarization phase functions have similar shapes as those of horizontally homogeneous planets. Fitting flux phase functions of a planet with belts and zones using a horizontally homogeneous planet could theoretically yield cloud top pressures that differ by a few hundred mbar from those derived from fitting polarization phase functions. In practice, however, observational errors and uncertainties in cloud properties would make such a fit unreliable. A cyclonic spot like Jupiter's Great Red Spot, covering a few percent of the disk, located in equatorial regions, and rotating in and out of the observer's view yields a temporal variation of a few percent in the broadband flux and a few percent in the degree of polarization. Polar hazes leave strong traces in the polarization of reflected starlight in spatially resolved observations, especially seen at phase angles near 90 • . Integrated across the planetary disk, polar hazes that cover only part of the planetary disk, change the broadband degree of polarization of the reflected light by a few percent. Such hazes have only small effects on locally reflected broadband fluxes and negligible effects on disk-integrated broadband fluxes. Conclusions. Deriving the presence of belts and zones in the atmospheres of gaseous exoplanets from broadband flux and polarization observations will be extremely difficult. Cyclonic spots could leave temporal changes in the broadband flux and polarization signals of a few percent. Polar hazes that cover a fraction of the planetary disk, and that are composed of small, Rayleigh scattering particles, change the broadband degree of polarization by at most a few percent.

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Section: Polar Haze Particlesmentioning

confidence: 99%

Flux and polarization signals of spatially inhomogeneous gaseous exoplanets

Karalidi

Stam

Guirado

2013

A&A

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“…At an altitude of 200 km, at which homogeneous nucleation begins according to Friedson et al (2002), Fig. 6 shows that pyrene mole fractions of 3 × 10 −5 and 4 × 10 −6 are required to condense 10% of the initial population in the north pole and near the equator, respectively.…”

Section: Implications For Haze Formation In the Stratosphere Of Jupitermentioning

confidence: 99%

“…Aromatic-based chemical schemes developed to investigate aerosol formation in polar regions (Wong et al 2000;Friedson et al 2002;Wong et al 2003) and in the northern equatorial belt (Lebonnois 2005) find their inspiration in combustion studies and models of polycyclic aromatic hydrocarbon (PAH) and soot formation in flames (Wang & Frenklach 1994). Several of the radical-neutral reactions considered have little or no energy entrance barrier and are therefore still relevant at the low temperatures characterizing the atmosphere of Jupiter.…”

Section: Introductionmentioning

confidence: 99%

“…As particles grow, they sediment under the effect of gravity until they reach the troposphere (Wong et al 2003). Friedson et al (2002) coupled the neutral chemical kinetics model of Wong et al (2000) with an aerosol microphysical model to examine the formation of polar haze with the intention of producing quantitative predictions of polar haze properties that can be compared with observations. Later the model was updated to include ion chemistry (Wong et al 2003).…”

Section: Introductionmentioning

confidence: 99%

“…However, as highlighted by Friedson (2002), much of the critical data for calculating homogeneous nucleation rate of three-and four-ring PAHs were unavailable. In this paper we present state-of-the-art laboratory experiments coupled to high-level theoretical calculations related to the thermodynamics and kinetics of the dimerization of anthracene (C 14 H 10 ).…”

Section: Introductionmentioning

confidence: 99%

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Insights into the role of polycyclic aromatic hydrocarbon condensation in haze formation in Jupiter’s atmosphere

Biennier

Sabbah

Chandrasekaran

et al. 2011

A&A

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Context. The haze in the atmosphere of Jupiter has been proposed to originate mostly from the condensation of low mass PAHs. Under this hypothesis, the transition of gas phase molecular species to solid particles is achieved by the formation of a critical nucleus composed of two small PAH molecules held together by van der Waals forces. Aims. Laboratory experiments coupled with theoretical calculations explore the thermodynamics and kinetics of PAH dimerization with the objective to assess this pathway in the production of nuclei of haze particles. Methods. We have performed experiments to identify the temperature range over which small PAH clusters form in supersaturated uniform supersonic flows. The kinetics of this formation has also been investigated. The chemical species present in the reactor are probed by a time-of-flight mass spectrometer equipped with a VUV laser for photoionisation of the neutral reagents and products. The experimental data were combined with theoretical calculations that employ careful consideration of the intermolecular interaction energies and intermolecular dynamics to estimate the binding energy, equilibrium constant, and rate constant. Results. We found that low-mass PAHs such as anthracene (C 14 H 10 ) and pyrene (C 16 H 10 ) can not homogeneously nucleate in the upper stratosphere at the altitude at which haze formation has been proposed to commence. Other chemical or physical processes should be considered to account for aerosol nuclei formation.

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The detection of benzene in Saturn's upper atmosphere

Koskinen

Moses

West

et al. 2016

Geophysical Research Letters

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The stratosphere of Saturn contains a photochemical haze that appears thicker at the poles and may originate from chemistry driven by the aurora. Models suggest that the formation of hydrocarbon haze is initiated at high altitudes by the production of benzene, which is followed by the formation of heavier ring polycyclic aromatic hydrocarbons. Until now there have been no observations of hydrocarbons or photochemical haze in the production region to constrain these models. We report the first vertical profiles of benzene and constraints on haze opacity in the upper atmosphere of Saturn retrieved from Cassini Ultraviolet Imaging Spectrograph stellar occultations. We detect benzene at several different latitudes and find that the observed abundances of benzene can be produced by solar‐driven ion chemistry that is enhanced at high latitudes in the northern hemisphere during spring. We also detect evidence for condensation and haze at high southern latitudes in the polar night.

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Models for Polar Haze Formation in Jupiter's Stratosphere

Cited by 77 publications

References 44 publications

Flux and polarization signals of spatially inhomogeneous gaseous exoplanets

Flux and polarization signals of spatially inhomogeneous gaseous exoplanets

Insights into the role of polycyclic aromatic hydrocarbon condensation in haze formation in Jupiter’s atmosphere

The detection of benzene in Saturn's upper atmosphere

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