Seasonal and long-term variations in Titan's stratospheric chemical composition
Résumé
Ten years after Cassini's Saturn orbit insertion, we look at the evolution of the thermal and chemical composition of Titan's atmosphere by analyzing Cassini CIRS spectra. In particular, we use CIRS data from 2004-2013 to derive the temperature structure [1,2,7] and the neutral chemistry at latitudes between 50°S and 50°N [2]. A peak in abundance in the North was observed around the northern spring equinox (NSE), with a rapid decrease after mid-2009, indicating that the vortex has shrunk. The fulfillment of one Titanian year of space and ground-based observations in 2010 provided us for the first time with the opportunity to evaluate the relative role of different physical processes in the long-term evolution of this complex environment [2-7], as also reported by other studies [10, 11].