Details

Autor(en) / Beteiligte

• Bell, Jared M.
• Bougher, Stephen W.
• Waite Jr, J. Hunter
• Ridley, Aaron J.
• Magee, Brian A.
• Mandt, Kathleen E.
• Westlake, Joseph
• DeJong, Anna D.
• Bar-Nun, Akiva
• Jacovi, Ronen
• Toth, Gabor
• De La Haye, Virginie
• Gell, David
• Fletcher, Gregory

Titel

Simulating the one-dimensional structure of Titan's upper atmosphere: 3. Mechanisms determining methane escape

Ist Teil von

• Journal of Geophysical Research, 2011-11, Vol.116 (E11), p.n/a, Article E11002

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2011

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• This investigation extends the work presented by Bell et al. (2010a, 2010b). Using the one‐dimensional (1‐D) configuration of the Titan Global Ionosphere‐Thermosphere Model (T‐GITM), we quantify the relative importance of the different dynamical and chemical mechanisms that determine the CH4 escape rates calculated by T‐GITM. Moreover, we consider the implications of updated Huygens Gas Chromatograph Mass Spectrometer (GCMS) determinations of both the 40Ar mixing ratios and 15N/14N isotopic ratios in work by Niemann et al. (2010). Combining the GCMS constraints in the lower atmosphere with the Ion Neutral Mass Spectrometer (INMS) measurements in work by Magee et al. (2009), our simulation results suggest that the optimal CH4 homopause altitude is located at 1000 km. Using this homopause altitude, we conclude that topside escape rates of 1.0 × 1010 CH4 m−2 s−1 (referred to the surface) are sufficient to reproduce the INMS methane measurements in work by Magee et al. (2009). These escape rates of methane are consistent with the upper limits to methane escape (1.11 × 1011 CH4 m−2 s−1) established by both the Cassini Plasma Spectrometer (CAPS) and Magnetosphere Imaging Instrument (MIMI) measurements of Carbon‐group ions in the near Titan magnetosphere. Key Points Investigate the mechanisms determining the methane escape simulated by T‐GITM Investigate methane escape estimates calculated by a 1‐D diffusion model Evaluate the impacts of the new Huygens GCMS data