Vertical profiles of temperature and abundance of some compounds on Titan from analysis of Cassini/CIRS limb spectra
Abstract
We present an analysis of Titan's spectra obtained by CIRS (Composite InfraRed Spectrometer) during the Titan Tb flyby (on December 13, 2004) and T3 flyby (on February 14, 2005). The Tb spectra were recorded near the equator (15°S) and the T3 spectra near the north pole (80°N). We mainly focus on limb spectra to retrieve vertically-resolved information on the temperature profile and on the abundance profiles of acetylene (C2H2), ethane (C2H6), and hydrogen cyanide (HCN). The determination of the abundance profile requires the knowledge of the temperature profile as a first step. We retrieve it from the emission of the ν4 methane band at 1305 cm-1 (7.7 microns), using an inversion algorithm of the radiative transfer equation. This algorithm makes use of both limb spectra and an average spectrum at nadir, which provides additional information at deeper levels. The retrieved thermal profile is then used to model observed spectra in the range 600-1000 cm-1 and derive the vertical profiles of the gaseous absorbers from the best fits of all limb and nadir spectra simultaneously.
- Publication:
-
SF2A-2005: Semaine de l'Astrophysique Francaise
- Pub Date:
- December 2005
- Bibcode:
- 2005sf2a.conf..133V