Advancing Our Understanding of Martian Proton Aurora through a
Coordinated Multi-Model Comparison Campaign
Abstract
Proton aurora are the most commonly observed yet least studied type of
aurora at Mars. In order to better understand the physics and driving
processes of Martian proton aurora, we undertake a multi-model
comparison campaign. We compare results from four different
proton/hydrogen precipitation models with unique abilities to represent
Martian proton aurora: Jolitz model (3-D Monte Carlo), Kallio model (3-D
Monte Carlo), Bisikalo/Shematovich et al. model (1-D kinetic Monte
Carlo), and Gronoff et al. model (1-D kinetic). This campaign is divided
into two steps: an inter-model comparison and a data-model comparison.
The inter-model comparison entails modeling five different
representative cases using similar constraints in order to better
understand the capabilities and limitations of each of the models.
Through this step we find that the two primary variables affecting
proton aurora are the incident solar wind particle flux and velocity. In
the data-model comparison, we assess the robustness of each model based
on its ability to reproduce a MAVEN/IUVS proton aurora observation. All
models are able to effectively simulate the data. Variations in modeled
intensity and peak altitude can be attributed to differences in model
capabilities/solving techniques and input assumptions (e.g., cross
sections, 3-D versus 1-D solvers, and implementation of the relevant
physics and processes). The good match between the observations and
multiple models gives a measure of confidence that the appropriate
physical processes and their associated parameters have been correctly
identified, and provides insight into the key physics that should be
incorporated in future models.