Monte Carlo Model Predictions of Energetic Ion Precipitation and Energy Deposition in the Martian Atmosphere

Friday, 19 December 2014
Rebecca Jolitz1, Robert J Lillis2, Shannon Curry3, Christopher Dennis Parkinson4 and Davin E Larson3, (1)University of California Berkeley, Berkeley, CA, United States, (2)UC Berkeley, Berkeley, CA, United States, (3)Space Sciences Laboratory, Berkeley, CA, United States, (4)University of Michigan, Ann Arbor, MI, United States
Energetic charged particle precipitation is an important source of energy to the Martian upper atmosphere. We use a Monte Carlo code to track a population of ions throughout the Martian atmosphere, predicting energy loss from collisional processes such as ionization, excitation, dissociation, etc. The model framework is open to multiple planetary-specific inputs (e.g. three-dimensional neutral densities, electric and magnetic fields) and uses an adaptive trace algorithm to accurately model collisions in both dense and sparse atmospheric regions. Applying predicted 3-D models of electric and magnetic fields from the Michigan Mars MHD code and 1-D neutral densities from the MTGCM model, we use this model to calculate global rates of collisional processes for proton and neutral hydrogen collisions in the Martian upper atmosphere. Future work will include generating three-dimensional ionization rates in areas of strong and weak crustal magnetic fields for typical isotropic and beamed solar energetic particle (SEP) events. This work has significant implications for our understanding of the solar wind interaction with Mars and long-term Martian atmospheric erosion, especially for comparing results with the upcoming Mars Atmosphere Volatile EvolutioN (MAVEN) mission.