Ground-based measurements of the methane distribution on Titan

Paulo F. Penteado, Caitlin A. Griffith

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Using spectra taken with NIRSPEC (Near Infrared Spectrometer) and adaptive optics on the Keck II telescope, we resolved the latitudinal variation of the 3 ν2 band of CH3 D at 1.56 μm. As CH3 D is less abundant than CH4 by a factor of 50 ± 10 × 10- 5, these CH3 D lines do not saturate in Titan's atmosphere, and are well characterized by laboratory measurements. Thus they do not suffer from the large uncertainties of the CH4 lines that are weak enough to be unsaturated in Titan. Our measurements of the methane abundance are confined to the latitude range of 32°S-18°N and longitudes sampled by a 0.04″ slit centered at ∼195°W. The methane abundance below 10 km is constant to within 20% in the tropical atmosphere sampled by our observations, consistent with the low surface insolation and lack of surface methane [Griffith, C.A., McKay, C.P., Ferri, F., 2008. Astrophys. J. 687, L41-L44].

Original languageEnglish (US)
Pages (from-to)345-351
Number of pages7
Issue number1
StatePublished - Mar 2010


  • Abundances
  • Atmospheres
  • Radiative transfer
  • Satellites
  • Spectroscopy
  • Titan

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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