Global distribution of Martian magnetosonic waves and their effects on ionospheric electrons

Magnetosonic waves are prevalent plasma waves in the Martian ionosphere and may play a significant role in driving ion escape. However, research on the global distribution of Martian magnetosonic waves and their effects on electrons in the ionosphere has been limited. This study aims to statistically investigate the global distribution of Martian magnetosonic waves and their effects on ionospheric electron density and temperature. Using observational data from the MAVEN mission spanning May 2015 to December 2023, we performed a statistical analysis and identified magnetosonic wave events based on magnetic field fluctuations. Wave occurrence rates, electron density, and electron temperature were mapped onto a 5^̧irc 5^̧irc longitude–latitude grid at different altitude intervals. We find that magnetosonic waves are predominantly concentrated in the northern hemisphere of Mars, with peak occurrence rates clustered within two primary regions: 20^̧irc–60^̧ircN in latitude and 90^̧irc–180^̧irc in longitude, and 0^̧irc–60^̧ircN in latitude and 200^̧irc–300^̧irc in longitude. At a given altitude, regions with frequent magnetosonic activity are associated with significantly lower electron densities compared to regions with weaker or no wave activity. The electron density depletion becomes more pronounced with increasing altitude and wave amplitude, reaching up to two orders of magnitude for waves $>1$ nT at 400–500 km. For electron temperature, the wave-induced modulation is altitude-dependent: below 300 km, increasing wave amplitude leads to a significant reduction in T_e and diminished spatial inhomogeneity; above 300 km, this decreasing trend in T_e becomes less evident, while larger amplitudes increase T_e spatial fluctuations. These results reveal a strong statistical anticorrelation between magnetosonic wave activity and ionospheric electron density, which is coupled with an altitude- and amplitude-dependent modulation of electron temperature. They provide novel observational evidence of the role of magnetosonic waves in regulating ionospheric plasma properties and potentially driving plasma escape. Further investigation is required to establish the causal relationship and underlying physical mechanisms.