Transport and Distribution of Sodium Ions in Mercury's Magnetosphere: Results From Multi‐Fluid MHD Simulations

Abstract Mercury is surrounded by a tenuous neutral exosphere composed primarily of sodium atoms, which can be continuously ionized. The production of sodium ions is concentrated on the dayside, and these ions can subsequently be transported to the magnetotail and flanks. MESSENGER spacecraft observations revealed dawn‐dusk asymmetric distributions of sodium ions . In this study, we investigate the circulation, distribution, and its influence on global magnetospheric convection with a two‐fluid MHD model, which is coupled with an empirical sodium exosphere profile as the source of . In particular, we aim to investigate if the dawn‐dusk asymmetries in distributions near the equator can be driven by internal mechanisms within the magnetosphere. Our findings indicate that (a) the observed dawn‐dusk asymmetric distributions can be driven by the separation of and flows, and (b) the Hall‐driven global convection preferentially transporting ions to the morning sector.