Reanalysis of Mars ionospheric electron density profiles from Mariner 9

The Mariner 9 radio occultation experiment acquired 118 profiles of dayside ionospheric electron density from 1971-2. Relative to the MGS dataset, which contains the only electron density profiles for Mars that are readily available to the public today, the Mariner 9 dataset has some unique characteristics. Profiles extend to 300-400 km, thereby probing the topside ionosphere better than the MGS profiles that typically terminate around 200 km. Profiles were acquired during the waning phase of a tremendous dust storm, when the ionospheric peak was 20-30 km higher than normal. Profiles are distributed globally, whereas MGS profiles are poleward of 60 degrees north latitude, and sample solar zenith angles as low as 47 degrees, whereas MGS was limited to 71 degrees and higher. We have digitized the Mariner 9 electron density profiles from their microfilm archive. Here we report on a broad scientific analysis of these profiles. We examine the dependence of electron densities in the M2 and M1 layers on solar zenith angle and flux, how the dust storm affected both peak altitude and ionopause altitude, and the presence of meteoric layers.