Response of Mars O+ pickup ions to the 8 March 2015 ICME: Inferences from MAVEN data-based models

Abstract

We simulate and compare three phases of the Mars-solar wind interaction with the 8 March interplanetary coronal mass ejection (ICME) event using Mars Atmosphere and Volatile EvolutioN (MAVEN) mission observations in order to derive heavy ion precipitation and escape rates. The MAVEN observations provide the initial conditions for three steady state MHD model cases, which reproduce the observed features in the solar wind density, velocity, and magnetic field seen along the MAVEN orbit. Applying the MHD results to a kinetic test particle model, we simulate global precipitation and escape maps of O+ during the (1) pre-ICME phase, (2) sheath phase, and (3) ejecta phase. We find that the Case 1 had the lowest precipitation and escape rates of 9.5 × 1025 and 4.1 × 1025 s-1, Case 2 had the highest rates of 9.5 × 1025 and 4.1 × 1025 s-1, and Case 3 had rates of 3.2 × 1025 and 1.3 × 1025 s-1, respectively. Additionally, Case 2 produced a high-energy escaping plume >10 keV, which mirrored corresponding STATIC observations.