Simulating the time-dependent response of Titan's upper atmosphere to periods of magnetospheric forcing

Abstract

We demonstrate that a simulation of Titan's upper atmosphere can exhibit significant short-term temperature variations when exposed to globally averaged plasma heating rates over periods of 8 Earth days (0.5 Titan days). Temperature enhancements can range from 16 K when exposed to column-integrated, orbit-averaged heating rates of 2.5 × 10⁸ eV/cm²/s up to 30 K when exposed to 5.0 × 10⁸ eV/cm²/s. Upon cessation of these plasma heating periods, the simulated upper atmosphere relaxes back to its original, unperturbed state after ∼10 Earth days (0.625 Titan days). Thus, we conclude that the variations in densities measured by the Ion Neutral Mass Spectrometer (INMS) above 1000 km during sequential flybys (i.e., those flybys separated by only 1 Titan day) can be potentially explained by periodic exposure of Titan to Saturn's plasma sheet.