Auroral electrons at Mars: upstream drivers and ionospheric impact
Journal Article
Overview
abstract
<p>Discrete aurorae have been observed at Mars by multiple spacecraft, including Mars Express, Mars Atmosphere and Volatile EvolutioN (MAVEN), and most recently the United Arab Emirates&#8217; Hope spacecraft.&#160; Meanwhile, there have been studies on the source particle responsible for producing these detectable aurorae, that is accelerated electrons or hotter solar wind electrons (termed &#8220;auroral electrons"). By utilizing empirical criteria to select auroral electrons established by Xu et al. [2022], we conduct statistical analyses of the impact of upstream drivers on the occurrence rate and electron fluxes of auroral electrons. We find the occurrence rate is well organized and increases with upstream dynamic pressure and weakly depends on the interplanetary magnetic field strength. Meanwhile, the integrated auroral electron flux is somewhat insensitive to the upstream drivers. In the meantime, the auroral emission is not the sole effect of electrons impacting the collisional atmosphere. Auroral electrons are expected to cause significant ionization and enhance the plasma density locally. In this study, we also quantify the ionospheric impact of auroral electron precipitation, specifically the thermal ion (O+, O2+, CO2+) density enhancement, with MAVEN observations and also modeling. Our results show the ion density to increase up to 1-2 orders of magnitude at low altitudes.</p>
