We investigated, for the first time, the impact of the disappearing solar wind (DSW) event [26–28 December 2022] on the deep nightside ionospheric species using MAVEN data sets. An enhanced plasma density has been observed in the Martian nightside ionosphere during extreme low solar wind density and pressure periods. At a given altitude, the electron density surged by ∼2.5 times, while for ions (NO⁺, O₂⁺, CO₂⁺, C⁺, N⁺, O⁺, and OH⁺), it enhanced by > 10 times, respectively, compared to their typical average quiet-time periods. This investigation suggests that an upward ionospheric expansion likely took place in a direct consequence to the contrasting low dynamic/magnetic pressure and relatively higher nightside ionospheric pressure (by 1–2 orders) causing an increased ionospheric density. Moreover, the day-to-night plasma transport may also be a contributing factor to the increased plasma density. Thus, this study offers a new insight about planetary atmosphere/ionosphere during extreme quiescent solar wind periods.

中文翻译：

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太阳风消失事件期间火星夜侧电离层响应：初步结果


我们首次使用 MAVEN 数据集研究了太阳风消失 （DSW） 事件 [2022 年 12 月 26 日至 28 日] 对深夜电离层物种的影响。在极低的太阳风密度和压力时期，在火星夜侧电离层中观察到等离子体密度增加。在给定的高度，电子密度激增了 ∼2.5 倍，而离子（NO ⁺ 、O ₂ ⁺ 、CO ₂ ⁺ 、C ⁺ 、N ⁺ 、O ⁺ 和 OH ⁺ ）与它们的典型平均静默期相比，它分别增加了 > 10 倍。这项研究表明，电离层向上膨胀可能是由于相对较低的动态/磁压和相对较高的夜电离层压力（1-2 个数量级）导致电离层密度增加的直接结果。此外，昼夜血浆转运也可能是血浆密度增加的一个因素。因此，这项研究为极端静止太阳风期间的行星大气/电离层提供了新的见解。