Impact of the 2018 Mars Global Dust Storm on the Ionospheric Peak: A Study Using a Photochemical Model

Abstract

We report the impact of the 2018 Mars global dust storm on the ionosphere, in particular, its peak altitude during the onset and growth phases of the event. A one-dimensional photochemical model is applied to estimate the ionospheric electron densities below 200 km using the measurements of in situ neutral densities and ionizing solar radiation by the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Our model results show that while the peak density of the ionosphere on the dawn side during the dust storm is hardly impacted, the altitude of the peak layer may be lifted by ∼10 km. The simulation results support the MAVEN radio occultation observations that there is a time delay in the response of the ionospheric peak altitude in the southern hemisphere (SH), compared with the northern hemisphere (NH) during the dust storm development. Although the 2018 global dust storm developed in the northern Martian mid-latitudes on 1 June and developed into a global dust event on 17 June, our study suggests that the impact on the ionospheric peak altitude near the equatorial and southern mid-latitudes became important only after 22 June. This suggests that there was a time-lag of about 3 weeks in the response of the Martian upper atmosphere of the SH to the dust storm that originated in the NH.