Exploring the effects of electron impact ionization on the Mars upper atmosphere

One of the major sources of energy into the nightside Martian ionosphere, electron precipitation, has historically been missing from 3D atmospheric models. By neglecting this process, not only do models miss out on an important source of ionization, but it is impossible to capture the dynamics that result from the interplay between the ion and neutral flows. We address this problem through the inclusion of an empirical electron impact ionization model in the Mars Global Ionosphere-Thermosphere model [Bougher et al., 2015] and the Laboratoire de Météorologie Dynamique (LMD) Mars GCM [Gonzalez-Galindo et. al., 2009]. Additionally, we use the magnetic field topology as specified by a Mars MHD model [Ma et al., 2004] to ensure an accurate representation of the magnetic field within the GCMs. The magnetic field acts as a shield to precipitating electrons where the field topology is closed, and a funnel that channels electrons into the atmosphere where the topology is open. Here we present a comparison between the GCMs run with and without the empirical electron impact ionization model. We examine how the effects of electron impact ionization depend on the magnetic topology as well as how impact ionization depends on the Mars season.