A Comparison of the Impacts of CMEs and CIRs on the Martian Dayside and Nightside Ionospheric Species

Measurements from the Mars Atmosphere and Volatile EvolutioN spacecraft orbiting Mars are used for investigating the impact of coronal mass ejections (CMEs) and corotating interaction regions (CIRs) on Martian ionospheric species. We have chosen 15 CME and 15 CIR events (2015-2020) at Mars from the existing catalogs. We have extensively analyzed the Martian dayside and nightside profiles of ionospheric species during each of the CME and CIR events. We have selected those orbit plasma density profiles which showed significant differences from the mean quiet-time profile during each event. The primary focus of this paper is to provide a comparative average scenario of the variation of Martian ionospheric species during CME and CIR events. A significant difference can be observed in the profiles of the Martian dayside and nightside ionospheric species (O+, O-2(+), CO2+, NO+, C+, N+, & OH+) during CMEs and CIRs in comparison to mean quiet-time profile. The difference is more prominent on the nightside compared to the dayside ionosphere. During CIRs, the nightside ion density is nearly one order of magnitude less (above 250 km) in comparison to CMEs. The mean peak altitude and density of the lighter ions (O+, C+, N+, & OH+) were at lower altitudes during the CIRs compared to CMEs. Therefore, this study suggests that during the declining phase of solar cycle (SC 24), the impact of CIRs on the Martian ionospheric species is more prominent compared to CMEs.