A procedure to analyze nonlinear density waves in Saturn's rings using several occultation profiles

摘要

Cassini radio science experiments have provided multiple occultation opticaldepth profiles of Saturn's rings that can be used in combination to analyzedensity waves. This paper establishes an accurate procedure of inversion of thewave profiles to reconstruct the wave kinematic parameters as a function ofsemi-major axis, in the nonlinear regime. This procedure is achieved fromsimulated data in the presence of realistic noise perturbations, to control thereconstruction error. By way of illustration we have applied our procedure tothe Mimas 5:3 density wave. We were able to recover precisely the kinematicparameters from the radio experiment occultation data in most of thepropagation region; a preliminary analysis of the pressure-corrected dispersionallowed us to determine new but still uncertain values for the opacity($K\simeq 0.02$ cm$^2$/g) and velocity dispersion of ($c_o\simeq 0.6$ cm/s) inthe wave region. Our procedure constitutes the first step in our plannedanalysis of the density waves of Saturn's rings. It is very accurate andefficient in the far-wave region. However, improvements are required within thefirst wavelength. The ways in which this method can be used to establishdiagnostics of ring physics are outlined.