Methance escape from Titan's atmosphere

R. V. Yelle, J. Cui, I. C.F. Müller-Wodarg

Research output: Contribution to journalArticlepeer-review

107 Scopus citations


Measurements of the mole fractions of CH4 and 40Ar by the Ion Neutral Mass Spectrometer on the Cassini orbiter are analyzed to determine the rate of vertical mixing in Titan's atmosphere and the escape flux of CH4. Analysis of the 40Ar data indicates an eddy mixing rate of 2-5 × 107 cm2 s-1, an order of magnitude smaller than previously determined from analysis of the CH4 distribution. The eddy profile determined from the 40Ar data implies that CH4 distribution is best explained by postulating that it is escaping the atmosphere at the diffusion limited rate of 2.5-3.0 × 109 cm-2 S-1, referred to the surface. This represents a significant loss of atmospheric CH4, smaller than but comparable to the photochemical destruction rate. The escape rate is much larger than predicted by the Jeans escape formula and vigorous nonthermal mechanisms are not apparent.

Original languageEnglish (US)
Article numberE10003
JournalJournal of Geophysical Research: Planets
Issue number10
StatePublished - Oct 20 2008

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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