Withers Paul, Flynn C L, Vogt M F, Mayyasi M, Mahaffy P, Benna M, Elrod M, McFadden J P, Dunn P, Liu G, Andersson L, England S
Department of Astronomy, Boston University, Boston, MA, USA.
Center for Space Physics, Boston University, Boston, MA, USA.
J Geophys Res Space Phys. 2019 Apr;124(4):3100-3109. doi: 10.1029/2018ja026266. Epub 2019 Apr 12.
Previous observations have shown that electron density and temperature in the dayside ionosphere of Mars vary between strongly and weakly magnetized regions of the planet. Here we use data from the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to examine whether dayside ion densities and ionospheric composition also vary. We find that O, , and densities above ~200 km are greater in strongly magnetized regions than in weakly magnetized regions. Fractional abundances of ion species are also affected. The ratio at 300-km altitude increases from ~0.5 in strongly magnetized regions to ~0.8 in weakly magnetized regions. Consequently, the plasma reservoir available for escape is fundamentally different between strongly magnetized and weakly magnetized regions.
先前的观测表明，火星日侧电离层中的电子密度和温度在该行星的强磁化区域和弱磁化区域之间存在差异。在此，我们使用火星大气与挥发物演化（MAVEN）航天器上的中性气体和离子质谱仪（NGIMS）的数据，来研究日侧离子密度和电离层组成是否也存在差异。我们发现，在高度约200公里以上，强磁化区域中的氧离子、氢离子和其他离子的密度高于弱磁化区域。离子种类的相对丰度也受到影响。在300公里高度处，氢离子与氧离子的比例从强磁化区域的约0.5增加到弱磁化区域的约0.8。因此，强磁化区域和弱磁化区域之间可用于逃逸的等离子体储存库存在根本差异。
