Possible evidence of seasonal variation in Titan's tropospheric methane distribution from Cassini radio occultation data
Abstract
The retrieval of Titan's atmospheric surface pressure from Cassini radio occultation data is sensitive to the tropospheric methane abundance, whose latitudinal distribution is not precisely known. For all available radio occultation datasets, we calculate the surface pressure under various hypothetical global methane distributions in an effort to constrain combinations of the global distribution of surface pressure and tropospheric methane abundance, which are meteorologically plausible. The Cassini data definitely rule out that the surface pressure and tropospheric methane abundance are globally uniform, so that a latitudinal variation in at least surface pressure or methane abundance is implied. The most internally consistent pair of surface pressure and methane abundance consists of a lower surface pressure and higher methane abundance in the summer hemisphere compared to the winter hemisphere. This is possible evidence of seasonal variation in the tropospheric methane distribution and may be a result of condensation and global methane transport across the equator by the meridional circulation
- Publication:
-
European Planetary Science Congress
- Pub Date:
- September 2013
- Bibcode:
- 2013EPSC....8...51T