Power Spectral Characteristics of Martian Ionospheric Irregularities

Abstract The intrinsic magnetic field of a planet plays a key role in its ionospheric dynamics. Mars lacks a global magnetic field, thus ionospheric plasma is weakly coupled to crustal and induced magnetic field. This thin and less dense ionosphere is conducive to generate electron density irregularities through various plasma instabilities. However, quantitative information of their spectral characteristics has remained limited. This paper presents the power spectral characteristics of Martian ionospheric irregularities based on 8 yr of observations from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. The analysis reveals that Martian irregularities exhibit a power-law spectrum with indices between 2 and 5, comparable to those observed in Earth’s ionosphere. The spectra are shallower in the direction perpendicular to the magnetic field, implying the presence of shorter spatial scales across the magnetic field. In regions of strong crustal magnetic field, irregularities exhibit systematically higher spectral indices. This information is crucial, giving modelers the opportunity to assess how Martian ionospheric irregularities affect transionospheric radio wave propagation, which has direct implications for future Mars missions.