Chemical composition of Titan’s atmosphere and ionosphere: Observations and the photochemical model

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2014-07, Vol.236, p.83-91
• Main Author: Krasnopolsky, Vladimir A.
• Format: Article
• Language: English
• Subjects: Atmospheres; Atmospheres, chemistry; Atmospheres, composition; Deposition; Hydrocarbons; Ionosphere; Ionospheres; Mathematical models; Nitriles; Photochemistry; Saturn satellites; Titan; Titan, atmosphere
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2014.03.041

•Self-consistent photochemical model of Titan’s atmosphere and ionosphere.•Vertical profiles of 83 neutral and 33 ion species from the surface to 1600km.•Differences between the model and observations are comparable to differences between the observations.•The model adequately presents chemical structure of Titan’s atmosphere and ionosphere. Basic observational data on hydrocarbons, nitriles, and ions on Titan are compared with predictions of the photochemical model. Uncertainties of the observed abundances and differences between the data from different instruments and observing teams are comparable with the differences between the observations and the model results. Main reactions of production and loss for each species are quantitatively assessed and briefly discussed. Formation of haze by polymerization of hydrocarbons and nitriles and recombination of heavy ions is calculated along with condensation of various species near the tropopause. Overall deposition is a layer of 300m thick for the age of the Solar System, and nitrogen constitutes 8% of the deposition. The model reproduces the basic observational data and adequately describes basic chemical processes in Titan’s atmosphere and ionosphere. The presented model results and the observational data may be used as a reference to chemical composition of Titan’s atmosphere and ionosphere.