Photochemistry of the atmosphere of Titan - Comparison between model and observations
Citations Over TimeTop 1% of 1984 papers
Abstract
The photochemistry of simple molecules containing carbon, hydrogen, nitrogen, and oxygen atoms in the atmosphere of Titan has been investigated using updated chemical schemes and our own estimates of a number of key rate coefficients. Proper exospheric boundary conditions, vertical transport, and condensation processes at the tropopause have been incorporated into the model. It is argued that he composition, climatology, and evolution of Titan's atmosphere are controlled by five major processes: (a) photolysis and photosensitized dissociation of CH4; (b) conversion of H to H2 and escape of hydrogen; (c) synthesis of higher hydrocarbons; (d) coupling between nitrogen and hydrocarbons; (e) coupling between oxygen and hydrocarbons. Starting with N2, CH4, and H2O, and invoking interactions with ultraviolet sunlight, energetic electrons, and cosmic rays, the model satisfactorily accounts for the concentrations of minor species observed by the Voyager IRIS and UVS instruments. Photochemistry is responsible for converting the simpler atmospheric species into more complex organic compounds, which are subsequently condensed at the tropopause and deposited on the surface. Titan might have lost 5.6 x 10(4), 1.8 x 10(3), and 4.0 g cm-2, or the equivalent of 8, 0.25, and 5 x 10(-4) bars of CH4, N2, and CO, respectively, over geologic time. Implications of abiotic organic synthesis on Titan for the origin of life on Earth are briefly discussed.
Related Papers
- → Correlation between stratospheric temperature, total ozone, and tropospheric weather systems(1994)73 cited
- → Calculating the global mass exchange between stratosphere and troposphere(1996)59 cited
- → Stratosphere‐troposphere ozone exchange observed with the Indian MST radar and a simultaneous balloon‐borne ozonesonde(1998)16 cited
- → Calculating the global mass exchange between stratosphere and troposphere(1996)6 cited
- → Change in the attenuation coefficient of light at the boundary between the troposphere and stratosphere(2022)