Simulation Results for Effects of Global and Regional Dust Storms on the Martian Hot O Corona and Photochemical Loss

We examine here for the first time the effects of both global and regional dust storms on the formation of the Martian hot O corona and associated photochemical loss of O. Our study is conducted by utilizing our integrated model framework, which couples our Martian hot O corona model with a multifluid magnetohydrodynamic model for Mars for the dusty and clear atmospheric condition cases. We present our results with the most up-to-date cross sections for the O(3P)-CO2 collisions. The main effect of dust storms on the ionosphere is the upward shift of the ionosphere on the dayside, which results in an increase in production of hot O at all altitudes above the ionospheric peak. However, the dust-induced inflation of the neutral upper atmosphere results in an enhancement in collisional loss of hot O and thus effectively suppresses the hot O density, reducing the global photochemical loss rate by ~28% for the global dust storm scenario. The relative density structure of the hot O corona does not show any significant changes, while its magnitude decreases at all altitudes.本研究首次探究了全球与区域性沙尘暴对火星热氧冕（Martian hot O corona）形成过程及氧的相关光化学损耗的影响。本研究采用自主构建的一体化模型框架开展，该框架将火星热氧冕模型与适配沙尘与清洁大气工况的火星多流体磁流体动力学（multifluid magnetohydrodynamic）模型进行耦合。本研究在结果分析中采用了O(³P)-CO₂碰撞的最新碰撞截面（cross sections）数据。沙尘暴对电离层（ionosphere）的主要影响为昼侧电离层向上抬升，这使得电离层峰值以上所有高度的热氧生成量均有所提升。然而，沙尘诱导的中性高层大气膨胀会加剧热氧的碰撞损耗，进而有效抑制热氧密度，在全球沙尘暴情景下可使全球光化学损耗率降低约28%。火星热氧冕的相对密度结构未出现显著变化，但其整体强度在所有高度均有所下降。