Crustal Magnetic Control of the Martian Oxygen Corona

Abstract

Crustal magnetic fields on Mars play a crucial role in regulating interactions between the solar wind and the upper atmosphere. While previous studies have mainly examined their effects on ionospheric plasma, their potential influence on the neutral atmosphere has remained largely unexplored. Here we present the first comprehensive assessment of how crustal magnetism affects the Martian oxygen corona. By combining Mars Atmosphere and Volatile EvolutioN (MAVEN) Neutral Gas and Ion Mass Spectrometer and Langmuir Probe and Waves observations with numerical modeling, we show that in regions of strong crustal magnetization, enhanced and electron densities, together with reduced electron temperature, create favorable conditions for the production of hot O through dissociative recombination. Model results indicate that the oxygen corona in strong‐field regions is about 36% denser than in weak‐field regions. By integrating the modeled upward hot O flux above the local escape energy at the exobase, we further find that the escape rate of neutral hot O is enhanced in strong‐field regions by about 38%. In addition, the elevated exospheric O density in strong‐field regions increases production, potentially facilitating solar wind pickup and enhancing escape above the exobase. These findings reveal that crustal magnetic fields indirectly modulate the Martian oxygen corona and can enhance both the escape of neutral hot O and the production of exospheric available for pickup escape through their effects on the upper atmospheric plasma environment.