Characteristics of Titan's stratospheric aerosols and condensate clouds from Cassini CIRS far-infrared spectra

Kok, Remco de; Irwin, Patrick; Teanby, N. A.; Nixon, C. A.; Jennings, Donald E.; Fletcher, Leigh N.; Howett, C. J. A.; Calcutt, S. B.; Bowles, Neil E.; Flasar, F. M.; Taylor, F. W.

doi:10.1016/j.icarus.2007.04.003

Cited by 89 publications

(47 citation statements)

References 58 publications

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“…Titan's atmosphere is photochemically active even at lower altitudes and leads to the formation of complex tholin-like potential prebiotic molecules due to the penetrating longer wavelength photons. This is consistent with observations of Titan's haze stretching between B500 km and B50 km above the surface 9 , containing several regions of haze (0, A, B and C) as recently characterized by the Cassini CIRS instrument 34,35 .…”

supporting

confidence: 92%

Photochemical activity of Titan’s low-altitude condensed haze

et al. 2013

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Titan, the largest moon of Saturn and similar to Earth in many aspects, has unique orangeyellow colour that comes from its atmospheric haze, whose formation and dynamics are far from well understood. Present models assume that Titan's tholin-like haze formation occurs high in atmosphere through gas-phase chemical reactions initiated by high-energy solar radiation. Here we address an important question: Is the lower atmosphere of Titan photochemically active or inert? We demonstrate that indeed tholin-like haze formation could occur on condensed aerosols throughout the atmospheric column of Titan. Detected in Titan's atmosphere, dicyanoacetylene (C 4 N 2 ) is used in our laboratory simulations as a model system for other larger unsaturated condensing compounds. We show that C 4 N 2 ices undergo condensed-phase photopolymerization (tholin formation) at wavelengths as long as 355 nm pertinent to solar radiation reaching a large portion of Titan's atmosphere, almost close to the surface.

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supporting

confidence: 92%

Photochemical activity of Titan’s low-altitude condensed haze

et al. 2013

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“…Haze is expected to be highly absorbing in this wavelength region, due to high imaginary refractive indices and small particle sizes (Khare et al, 1984), and hence the non-scattering nature of the haze particles seems a reasonable assumption. The vertical profile is consistent with the southern profiles of de Kok et al (2007) and with Tomasko et al (2008b). Above an altitude of 80 km this profile has a scale height of 65 km, whereas below 80 km the haze scale height is identical to the atmospheric pressure scale height.…”

Section: Modelsupporting

confidence: 81%

“…We use far-infrared spectra between 250-550 cm −1 from the Cassini Composite Infrared Spectrometer (CIRS) (Flasar et al, 2004), with a spectral resolution of 13 Teanby, 2007;de Kok et al, 2007). The field-of-view (FOV) of the limb measurements is 53 km, which is taken into account by calculating spectra at 5 tangent altitudes within the FOV and weighing them according to the spatial response of the CIRS detector .…”

Section: Observationsmentioning

confidence: 99%

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Far-infrared opacity sources in Titan’s troposphere reconsidered

Kok

Irwin

Teanby

2010

Icarus

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“…As stated earlier the heavy negative ion density increased with depth in the atmosphere with the highest masses and number densities at the minimum altitude 950 km probed by Cassini . Such increases likely continue to lower altitudes and perhaps ultimately to maximum densities of aerosol cloud layers 100-200 km or lower (de Kok et al, 2007) above the surface. Lavvas et al Q008a,b developed a photochemical model of Titan's atmosphere which extended from the surface to the upper atmosphere 2-1400 krn altitude.…”

Section: Transport To Lower Atmosphere and Surface As Aerosolsmentioning

confidence: 99%