Variability of the Martian Ionosphere Observed by MAVEN and Comparison with 3D Multi-fluid MHD Model

Operating for more than 2 Mars years, the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has provided a unique opportunity to study the variability of the Martian upper atmosphere and ionosphere and their interaction with the solar wind under various conditions. This work presents the observed variability of the upper ionosphere, especially the region near the main ionospheric peak, for the entire period of the mission using the Neutral Gas and Ion Mass Spectrometer (NGIMS) measurements. As the nominal dayside peak is located lower than the MAVEN periapsis, the in situ detections of the peaks by MAVEN are concentrated near the terminator regions, where the peak altitude rises above the spacecraft's periapsis, allowing us to explore the peak structure at the high solar zenith angle region. We compare the observed variability of the ionospheric structure with our state-of-the-art 3D multi-fluid magnetohydrodynamic (MHD) model. We utilize available estimations of the solar wind parameters by MAVEN for the cases considered to investigate the response of the ionosphere. Our model's simulated results are compared with the plasma observations taken by the MAVEN instruments and published results from other existing state-of-the-art MHD models.