Actinic fluxes in Titan's atmosphere, from one to three dimensions: Application to high‐latitude composition

Lebonnois, Sébastien; Toublanc, D.

doi:10.1029/1999je001056

Cited by 23 publications

(25 citation statements)

References 12 publications

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“…In particular, the enrichment in the high northern latitudes in most species is not yet understood. In a previous study (Lebonnois and Toublanc 1999), we developed a three-dimensional description of the ultraviolet flux to test the latitudinal sensitivity of composition profiles obtained with a one-dimensional photochemical model. This study showed that radiation and chemistry alone could not explain the observations.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Variations of Titan's Atmospheric Composition

Lebonnois

Toublanc²,

Hourdin

et al. 2001

Icarus

159

126

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Section: Introductionmentioning

confidence: 99%

Seasonal Variations of Titan's Atmospheric Composition

Lebonnois

Toublanc²,

Hourdin

et al. 2001

Icarus

159

126

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“…For instance, variability in the EUV/UV radiation received at Mars has been directly linked to observed changes in the species density distribution (Bougher et al 2015). Early photochemical models predicted an increase in CH 4 photodissociation by as much as 75% due to seasonal variations (Lebonnois & Toublanc 1999). Latitudinal differences in composition were also proposed to exist over the seasons as a result of changing wind patterns (Lebonnois et al 2001(Lebonnois et al , 2003.…”

Section: Introductionmentioning

confidence: 99%

The Role of Nitrogen in Titan’s Upper Atmospheric Hydrocarbon Chemistry Over the Solar Cycle

Luspay‐Kuti

Mandt

Westlake

et al. 2016

ApJ

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Titan's thermospheric photochemistry is primarily driven by solar radiation. Similarly to other planetary atmospheres, such as Mars', Titan's atmospheric structure is also directly affected by variations in the solar extreme-UV/UV output in response to the 11-year-long solar cycle. Here, we investigate the influence of nitrogen on the vertical production, loss, and abundance profiles of hydrocarbons as a function of the solar cycle. Our results show that changes in the atmospheric nitrogen atomic density (primarily in its ground state N( 4 S)) as a result of photon flux variations have important implications for the production of several minor hydrocarbons. The solar minimum enhancement of CH 3 , C 2 H 6 , and C 3 H 8 , despite the lower CH 4 photodissociation rates compared with solar maximum conditions, is explained by the role of N( 4 S). N( 4 S) indirectly controls the altitude of termolecular versus bimolecular chemical regimes through its relationship with CH 3 . When in higher abundance during solar maximum at lower altitudes, N( 4 S) increases the importance of bimolecular CH 3 + N( 4 S) reactions producing HCN and H 2 CN. The subsequent remarkable CH 3 loss and decrease in the CH 3 abundance at lower altitudes during solar maximum affects the overall hydrocarbon chemistry.

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“…It was first suggested that this unexpected enrichment may be due to accumulation of compounds in the polar night, due to seasonal inhibition of photochemical processes by lack of ultraviolet flux (Yung 1987). Lebonnois & Toublanc (1999) showed that this process was not efficient enough to explain the observed enrichment, using a three-dimensional computation of actinic fluxes (i.e. photodissociating fluxes) in Titan's atmosphere and a one-dimensional photochemical model adapted to any latitude.…”

Section: Composition and Dynamicsmentioning

confidence: 99%

The coupling of winds, aerosols and chemistry in Titan's atmosphere

Lebonnois

Rannou

Hourdin

2008

Phil. Trans. R. Soc. A.

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The atmosphere of Titan is a complex system, where thermal structure, radiative transfer, dynamics, microphysics and photochemistry are strongly coupled together. The global climate model developed over the past 15 years at the Pierre-Simon Laplace Institute has been exploring these different couplings, and has demonstrated how they can help to interpret the observed atmospheric structure of Titan's lower atmosphere (mainly in the stratosphere and troposphere). This review discusses these interactions, and our current understanding of their role in the context of this model, but also of other available works. The recent Cassini results, and the importance of the production mechanisms for Titan's haze, have put forward the need to explore the mesosphere and the couplings between upper and lower atmosphere, as well as the current limits of available models.

show abstract

Actinic fluxes in Titan's atmosphere, from one to three dimensions: Application to high‐latitude composition

Cited by 23 publications

References 12 publications

Seasonal Variations of Titan's Atmospheric Composition

Seasonal Variations of Titan's Atmospheric Composition

The Role of Nitrogen in Titan’s Upper Atmospheric Hydrocarbon Chemistry Over the Solar Cycle

The coupling of winds, aerosols and chemistry in Titan's atmosphere

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