Numerical Analysis of Io's Atmospheric Behavior during Eclipse Based on a Model Boltzmann Equation

Abstract

Unsteady behavior of Io's atmosphere caused by condensation and sublimation of SO[2] (the main atmospheric component) during and after eclipse is studied on the basis of kinetic theory. A deterministic computation for a model Boltzmann equation by means of a finite-difference method is performed to obtain the time evolution of the profiles of macroscopic quantities (density, flow velocity, and temperature) in high resolution. As a result, the transient wave motion and oscillatory behavior in the profiles are clarified. To concentrate on the dominant effect of the noncondensable gas (SO or O[2] ), other effects in the real atmosphere (e.g., plasma impingement, chemical reactions, etc.) are all omitted in the present analysis. Despite those simplifications, the overall behavior of the atmospheric column is similar to the more realistic result of the previous DSMC analysis in C. H. Moore et al., Icarus 201, 585 (2009).