The Response of the Martian Thermosphere/Ionosphere to Enhanced Fluxes of Soft X Rays

We investigate the response of the thermosphere/ionosphere of Mars to enhanced fluxes of solar soft x rays, as have been measured by the SNOE satellite and the SEE instrument on TIMED. We model the Martian upper atmosphere for both high and low solar activities, with fluxes from both Hinteregger and Tobiska. We find that the lower peak in the electron density profile is increased, especially at high solar activity. The odd nitrogen densities in the lower thermosphere are enhanced, but the NO densities remain relatively constant. Only the N densities are significantly larger. Thus larger fluxes of solar soft x rays cannot account for the large NO densities measured by Viking 1 below 140 km, but can account for the often prominent peak seen below the main ionospheric peak by the MGS radio occultation measurements.