TITAN'S UPPER ATMOSPHERE from CASSINI/UVIS SOLAR OCCULTATIONS

Fernando J. Capalbo, Yves Bénilan, Roger Yelle, Tommi T. Koskinen

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Titan's atmosphere is composed mainly of molecular nitrogen, methane being the principal trace gas. From the analysis of 8 solar occultations measured by the Extreme Ultraviolet channel of the Ultraviolet Imaging Spectrograph (UVIS) on board Cassini, we derived vertical profiles of N2 in the range 1100-1600 km and vertical profiles of CH4 in the range 850-1300 km. The correction of instrument effects and observational effects applied to the data are described. We present CH4 mole fractions, and average temperatures for the upper atmosphere obtained from the N2 profiles. The occultations correspond to different times and locations, and an analysis of variability of density and temperature is presented. The temperatures were analyzed as a function of geographical and temporal variables, without finding a clear correlation with any of them, although a trend of decreasing temperature toward the north pole was observed. The globally averaged temperature obtained is (150 ± 1) K. We compared our results from solar occultations with those derived from other UVIS observations, as well as studies performed with other instruments. The observational data we present confirm the atmospheric variability previously observed, add new information to the global picture of Titan's upper atmosphere composition, variability, and dynamics, and provide new constraints to photochemical models.

Original languageEnglish (US)
Article number86
JournalAstrophysical Journal
Volume814
Issue number2
DOIs
StatePublished - Dec 1 2015

Fingerprint

occultation
spectrographs
Titan
upper atmosphere
temperature
vertical profile
profiles
Titan atmosphere
trace gas
poles
methane
trends
nitrogen
atmosphere
gases
effect
analysis

Keywords

  • occultations
  • planets and satellites: atmospheres
  • planets and satellites: composition
  • planets and satellites: individual (Titan)
  • techniques: imaging spectroscopy

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

TITAN'S UPPER ATMOSPHERE from CASSINI/UVIS SOLAR OCCULTATIONS. / Capalbo, Fernando J.; Bénilan, Yves; Yelle, Roger; Koskinen, Tommi T.

In: Astrophysical Journal, Vol. 814, No. 2, 86, 01.12.2015.

Research output: Contribution to journalArticle

Capalbo, Fernando J. ; Bénilan, Yves ; Yelle, Roger ; Koskinen, Tommi T. / TITAN'S UPPER ATMOSPHERE from CASSINI/UVIS SOLAR OCCULTATIONS. In: Astrophysical Journal. 2015 ; Vol. 814, No. 2.
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