Ionospheric plasma density data from the Planar Langmuir Probe onboard the CHAllenging Minisatellite Payload (CHAMP) are used to investigate the latitudinal profile of the ionospheric plasma density. Along with the well-known profiles with features of the equatorial ionization anomaly and equatorial plasma bubbles, a third type is observed as smooth profiles with large-scale deep equatorial trough (DET) where the plasma density is extremely low. A global survey focusing on magnetically quiet conditions reveals that the DET profiles are generally a post-sunset phenomenon, and their appearance depends on longitude and season. During equinoxes in active solar years, the strong pre-reversal enhancement electric field is believed to uplift the ionosphere and produce the DET profiles. While around June solstice, the DET profiles are clustered at W– E longitude, where the zonal electric field is weak but the magnetic meridional component of the neutral wind is most significant. The SAMI2 model is then employed to simulate the ionospheric plasma distribution in the magnetic meridional plane with enhanced neutral wind, which successfully reproduced the main features of the observed DET profile. The results indicate that the neutral wind can obviously affect the equatorial ionosphere by transporting plasma in the magnetic flux tube through neutral-ion interaction. The neutral wind is previously known to work with the inclined magnetic field at mid-latitude, while this study emphasizes its effect around the magnetic equator especially when the electric field forcing () is weak or absent.

中文翻译：

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CHAMP观测中强经向中性风在赤道深部电离槽形成中的作用

来自挑战小卫星有效载荷 (CHAMP) 上的平面朗缪尔探测器的电离层等离子体密度数据用于研究电离层等离子体密度的纬度分布。除了众所周知的具有赤道电离异常和赤道等离子体气泡特征的剖面外，还观察到第三种类型，即等离子体密度极低的具有大尺度深赤道槽（DET）的光滑剖面。一项针对磁静条件的全球调查显示，DET 剖面通常是日落后现象，其外观取决于经度和季节。在活跃太阳年的分点期间，强烈的反转前增强电场被认为会抬升电离层并产生 DET 剖面。在六月至左右，DET 剖面聚集在W- E 经度，纬向电场较弱，但中性风的磁子午线分量最显着。然后采用 SAMI2 模型模拟磁子午面增强中性风的电离层等离子体分布，成功再现了观测到的 DET 剖面的主要特征。结果表明，中性风通过中性离子相互作用在磁通量管中输送等离子体，对赤道电离层产生明显影响。先前已知中性风在中纬度与倾斜磁场一起工作，而这项研究强调了它在磁赤道周围的影响，特别是当电场强迫 ( ) 很弱或不存在时。