Titan's surface and troposphere, investigated with ground-based, near-infrared observations

Caitlin Griffith, Tobias Owen, Richard Wagener

Research output: Contribution to journalArticle

120 Citations (Scopus)

Abstract

New observations of Titan's near-infrared spectrum (4000-5000 cm-1) combined with points taken from Fink and Larson's (1979) spectrum (4000-12500 cm-1) provide information on Titan's haze, possible clouds, surface albedo, and atmospheric abundance of H2. In the near-infrared, the main features in Titan's spectrum result from absorption of solar radiation by CH4. The strength of this absorption varies considerably with wavelength, allowing us to probe various atmospheric levels down to the surface itself by choosing specific wavelengths for analysis. At 4715 cm-1, the pressure-induced S(1) fundamental band of H2 lies in the wings of CH4 bands. Based on current values for the CH4 line parameters, Titan's spectrum can be best interpreted with a volume mixing ratio of H2 between 0.5 and 1.0%. Our observations suggest the existence of an optically thin CH4 cloud layer. The optical depths that we derive for Titan's haze and clouds are small enough to allow us to sense the surface of Titan at 4900, 6250, and 7700 cm-1. The most plausible interpretation of the albedos determined at these wavenumbers suggests a surface dominated by "dirty" water ice. A global ethane ocean is not compatible with these albedos.

Original languageEnglish (US)
Pages (from-to)362-378
Number of pages17
JournalIcarus
Volume93
Issue number2
DOIs
StatePublished - 1991
Externally publishedYes

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Titan
troposphere
near infrared
albedo
haze
wavelength
ethane
solar radiation
mixing ratios
wavelengths
mixing ratio
wings
optical thickness
optical depth
oceans
ice
infrared spectra
probe
probes
ocean

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Titan's surface and troposphere, investigated with ground-based, near-infrared observations. / Griffith, Caitlin; Owen, Tobias; Wagener, Richard.

In: Icarus, Vol. 93, No. 2, 1991, p. 362-378.

Research output: Contribution to journalArticle

Griffith, Caitlin ; Owen, Tobias ; Wagener, Richard. / Titan's surface and troposphere, investigated with ground-based, near-infrared observations. In: Icarus. 1991 ; Vol. 93, No. 2. pp. 362-378.
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