Saturn's stratospheric equatorial oscillation and wave activity through the Cassini epoch

International audienceWe study the evolution of Saturn's Quasi-Periodic Oscillation, a dynamical phenomenon observed in Saturn's stratosphere that has counterparts in Jupiter and the Earth stratospheres as well. Thermal infrared spectra acquired by Cassini/CIRS in limb viewing geometry in 2015 are used to derive 2-D latitude-pressure temperature and thermal wind maps in Saturn's stratosphere. These maps are compared to previous observations from 2005 and 2010 to characterize and study the evolution of the vertical structure of Saturn's equatorial oscillation. This phenomenon is thought to result from the interaction between upward-propagating waves and the mean zonal flow, but little is known on Saturn's stratospheric wave activity. CIRS nadir spectra are then used to map stratospheric temperatures with longitude and characterize planetary waves in the tropical region (20N-20S)