Wavelike perturbations in Titan's ionosphere and their compositional variation: A preliminary survey of Cassini Ion Neutral Mass Spectrometer measurements

Wavelike perturbations in the ionosphere of Titan, the largest satellite of Saturn, are explored based on the Cassini Ion Neutral Mass Spectrometer (INMS) measurements. Strong wavelike perturbations are identified for more than twenty ion species, from simple ones such as N+ and CH4+ to complex ones such as C2H3CNH+ and C4H7+. Simultaneous wavelike perturbations in background N-2, indicative of atmospheric gravity waves, are also observed, motivating us to speculate that the INMS-derived ion perturbations are wave-driven. The amplitudes of the ion perturbations are found to be larger than that of the N-2 perturbations. Clear compositional variation is revealed by the data: heavier ion species exhibit greater amplitudes. Such observations might be understood based on considerations either of force balance or chemical loss in Titan's ionosphere.