The detached haze layer in Titan's mesosphere

Panayotis Lavvas, Roger Yelle, Véronique Vuitton

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

By comparing observations from the Cassini imaging system, UV spectrometer, and Huygens atmospheric structure instrument, we determine an apparent radius of ∼40 nm, an imaginary index <0.3 at 187.5 nm and a number density of ∼30 particles cm-3 for the detached haze layer at 520 km in Titan's mesosphere. We point out that the detached haze layer is coincident with a local maximum in the measured temperature profile and show that the temperature maximum is caused by absorption of sunlight in the detached haze layer. This rules out condensation as the source of the layer. The derived particle size is in good agreement with that estimated for the size of the monomers in the aggregate particles that make up the main haze layer. Calculations of the sedimentation velocity of the haze particles coupled with the derived number density imply a mass flux 2.7 - 4.6 × 10- 14   g cm- 2 s- 1, which is approximately equal to the mass flux required to explain the main haze layer. Because the aerosol size and mass flux derived for the detached layer agree with those determined for the main layer, we suggest that the main haze layer in Titan's stratosphere is formed primarily by sedimentation and coagulation of particles in the detached layer. This implies that high-energy radical and ion chemistry in the thermosphere is the main source of haze on Titan.

Original languageEnglish (US)
Pages (from-to)626-633
Number of pages8
JournalIcarus
Volume201
Issue number2
DOIs
StatePublished - Jun 2009

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haze
Titan
mesosphere
particle size
sedimentation
atmospheric structure
thermosphere
sunlight
coagulation
stratosphere
temperature profile
temperature profiles
condensation
aerosols
spectrometer
monomers
spectrometers
chemistry
radii

Keywords

  • Atmospheres
  • structure
  • Titan

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

The detached haze layer in Titan's mesosphere. / Lavvas, Panayotis; Yelle, Roger; Vuitton, Véronique.

In: Icarus, Vol. 201, No. 2, 06.2009, p. 626-633.

Research output: Contribution to journalArticle

Lavvas, Panayotis ; Yelle, Roger ; Vuitton, Véronique. / The detached haze layer in Titan's mesosphere. In: Icarus. 2009 ; Vol. 201, No. 2. pp. 626-633.
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