DIX Planetary Science Seminar

Titan hosts a dense atmosphere mainly composed of nitrogen and methane. It features a rich photochemical activity mainly initiated by solar UV photons, which produces many hydrocarbons, nitriles and ultimately organic hazes. During its 29.5 years revolution around the Sun, Titan's atmosphere undergoes significant seasonal and latitudinal variations of insolation which can affect its photochemistry and its dynamics.

The Cassini mission (2004-2017) allowed to monitor Titan's atmosphere from its northern winter to its summer solstice. Mid-IR (9-17 mm) spectroscopic observations from the Cassini/CIRS measurements showed clear seasonal changes in temperature and abundance of photochemical species, especially in the upper stratosphere and mesosphere (120 – 600 km). However, seasonal changes in the lower stratosphere (50 – 120 km) are not well known.

In this seminar, I will present investigations of Titan's lower stratosphere using Cassini/CIRS far-IR spectra (17 - 1000 mm). I will discuss the seasonal temperature and composition changes in this region and show how they can help us to understand chemical and dynamical processes of Titan's atmosphere.