Effect of the 2018 Martian Global Dust Storm on the Main Species in the Upper Ionosphere: Observations and Simulations

Martian global dust storms have significant influences on its atmosphere and ionosphere. In this research, the behavior of O-2(+), CO2+, and O+ density profiles during the 2018 global dust storm is studied based on the observations of Neutral Gas and Ion Mass Spectrometer (NGIMS) onboard Mars Atmosphere and Volatile Evolution. The observations show increased CO2+ density, decreased O+ density, and relatively stable O-2(+) density at 170-500 km during the dust storm. Using a photochemical model, we reproduced the behavior of O-2(+), CO2+ density at 170-200 km during the dust storm based on the behaviors of NGIMS observed neutral density profiles. The behaviors of those neutral and ion density profiles should be the combined effects of the variations of latitude, longitude, season, local time, Solar Zenith Angle (SZA), and the activity of the global dust storm. Two different methods, one based on the Mars Climate Database and another based on a parametric model, are used to remove the effects of latitude, longitude, season, local time, and SZA variations on the neutral atmosphere and ionosphere. Both methods indicate that O-2(+) density at 170-200 km should increase, rather than stay unchanged under the 2018 global dust storm-specified effect.