Electron density variability in the day-side ionosphere of Mars: The role of gravity waves

Abstract

ABSTRACT Mars Atmosphere and Volatile EvolutioN (MAVEN) has observed oscillations in the density, velocity, and temperature of ionospheric plasma on Mars. Atmospheric gravity waves can be an underlying mechanism. We propose a linearized wave–electron interaction model adopting a Wentzel–Kramers–Brillouin approximation to explore the electron density variations in the Martian day-side ionosphere for two regions, which are dominated by crustal magnetic fields and horizontal draped interplanetary magnetic fields. Our model results reveal that the electron density fluctuations associated with the crustal magnetic fields and the draped magnetic fields range from ∼ 40 per cent to ∼ 83 per cent and ∼ 29 per cent to ∼ 125 per cent, respectively. The wave-induced vertical electron flux peaks occur in a region ranging from ∼ 115 km to ∼ 179 km altitude. These results are comparable to the satellite observations. We further investigate the effect of the Martian magnetic topology on the wave-induced electron fluxes and demonstrate that the electron motions associated with the propagating gravity waves can be significantly influenced by the magnetic field orientations. The wave-induced variations in the electron temperature, ion density, and magnetic field combined with a comprehensive gravity wave model will be studied in further work.