资源环境科技发展态势分析平台

In a seminal analysis, Fuselier et al. (2020) combined subsolar in situ magnetosheath plasma observations with remote energetic neutral atom (ENA) observations to derive an exospheric neutral density of 11 cm^-3 in the vicinity of the subsolar magnetopause. This commentary extends the analysis of Fuselier et al. to (1) employ predicted and observed magnetosheath plasma parameters at times other than those immediately following an MMS magnetopause crossing, (2) take into account the component of the plasma bulk flow transverse to the ENA spacecraft’s line-of-sight through the flank magnetosheath, and (3) consider the cooling that results from the antisunward expansion of the magnetosheath plasma. With these additional considerations, subsolar exospheric neutral densities rise by a factor of 4.1 to 4.5 to 45-50 cm^-3, consistent with results from previous studies.