Seasonal variations in Titan's stratosphere observed with Cassini/CIRS: temperature, trace molecular gas and aerosol mixing ratio profiles
Abstract
Titan's northern spring equinox occurred in August 2009. General Circulation Models (e.g. Lebonnois et al., 2012) predict strong modifications of the global circulation in this period, with formation of two circulation cells instead of the pole-to-pole cell that occurred during northern winter. This winter single cell, which had its descending branch at the north pole, was at the origin of the enrichment of molecular abundances and high stratopause temperatures observed by Cassini/CIRS at high northern latitudes (e.g. Achterberg et al., 2011, Coustenis et al., 2010, Teanby et al., 2008, Vinatier et al., 2010). The predicted dynamical seasonal variations after the equinox have strong impact on the spatial distributions of trace gas, temperature and aerosol abundances.
We will present here an analysis of CIRS limb-geometry datasets acquired in 2010 and 2011 that we used to monitor the seasonal evolution of the vertical profiles of temperature, molecular (C2H2, C2H6, HCN, ...) and aerosol abundances. References: Achterberg, R. K. et al.: “Temporal variations of Titan's middle atmospheric temperatures from 2004 to 2009 observed with Cassini/CIRS”. 2010, Icarus 211, 686-698. Coustenis, A. et al.: “Titan trace gaseous composition from CIRS at the end of the Cassini-Huygens prime mission. 2010, Icarus 207, 461-476. Lebonnois, S., et al.: "Titan global climate model: a new 3-dimensional version of the IPSL Titan GCM". Icarus, In press. Vinatier, S. et al.: “Analysis of Cassini/CIRS limb spectra of Titan acquired during the nominal mission: I. Hydrocarbons, nitriles and CO2 vertical mixing ratio profiles”. 2010, Icarus 205, 559-570. Teanby, N. A., et al.: Global and temporal variations in hydrocarbons and nitriles in Titan's stratosphere for northern winter observed by Cassini/CIRS. 2008, Icarus 193, 595-611.- Publication:
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Titan Through Time; Unlocking Titan's Past, Present and Future
- Pub Date:
- April 2012
- Bibcode:
- 2012ttt..work...45V