Methance escape from Titan's atmosphere

Roger Yelle, J. Cui, I. C F Müller-Wodarg

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

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: Space Physics
Volume113
Issue number10
DOIs
StatePublished - Oct 20 2008

Fingerprint

Titan atmosphere
Titan
escape
atmosphere
Mass spectrometers
Ions
Fluxes
eddy
vortices
vertical mixing
mass spectrometers
destruction
spectrometer
rate
atmospheres
ion
profiles
ions

ASJC Scopus subject areas

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

Cite this

Methance escape from Titan's atmosphere. / Yelle, Roger; Cui, J.; Müller-Wodarg, I. C F.

In: Journal of Geophysical Research: Space Physics, Vol. 113, No. 10, E10003, 20.10.2008.

Research output: Contribution to journalArticle

Yelle, Roger ; Cui, J. ; Müller-Wodarg, I. C F. / Methance escape from Titan's atmosphere. In: Journal of Geophysical Research: Space Physics. 2008 ; Vol. 113, No. 10.
@article{dee65178fa4f4f3ca7c558fec3979962,
title = "Methance escape from Titan's atmosphere",
abstract = "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.",
author = "Roger Yelle and J. Cui and M{\"u}ller-Wodarg, {I. C F}",
year = "2008",
month = "10",
day = "20",
doi = "10.1029/2007JE003031",
language = "English (US)",
volume = "113",
journal = "Journal of Geophysical Research: Space Physics",
issn = "2169-9380",
publisher = "Wiley-Blackwell",
number = "10",

}

TY - JOUR

T1 - Methance escape from Titan's atmosphere

AU - Yelle, Roger

AU - Cui, J.

AU - Müller-Wodarg, I. C F

PY - 2008/10/20

Y1 - 2008/10/20

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=57649129448&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=57649129448&partnerID=8YFLogxK

U2 - 10.1029/2007JE003031

DO - 10.1029/2007JE003031

M3 - Article

AN - SCOPUS:57649129448

VL - 113

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9380

IS - 10

M1 - E10003

ER -