C₂N₂ vertical profile in Titan's stratosphere

In this paper, we present the first measurements of the vertical distribution of cyanogen (C₂N₂) in Titan’s lower atmosphere at different latitudes and seasons, us- ing Cassini/CIRS far-IR data. We also study the vertical distribution of three other minor species detected in our data: methylacetylene (C₃H₄), diacetylene (C₄H₂) and H₂O, in order to compare them to C₂N₂, but also to get an overview of their seasonal and meridional variations in Titan’s lower stratosphere from 85 km to 225 km. We measured an average volume mixing ratio of C₂N₂ of 6.2 ± 0.8 × 10⁻¹¹ at 125 km at the equator, but poles exhibit a strong enrichment in C₂N₂ (up to a factor 100 com- pared to the equator), greater than what was measured for C₃H₄ or C₄H₂ . Measuring C₂N₂ profiles provides constraints on the processes controlling its distribution, such as bombardment by Galactic Cosmic Rays which seem to have a smaller influence on C₂N₂ than predicted by photochemical models.