Disturbance Neutral Winds Effects on the Ionospheric Strip‐Like Bulge at Lower‐Middle Latitudes

• Published in: Journal of geophysical research. Space physics 2022-08, Vol.127 (8), p.n/a
• Main Authors: Wan, Xin, Zhong, Jiahao, Zhang, Shun‐Rong, Xiong, Chao, Wang, Hui, Liu, Yiwen, Huang, Fuqing, Li, Qiaoling, Kuai, Jiawei, Chen, Jiawen, Hao, Yongqiang
• Format: Article
• Language: English
• Subjects: Band structure of solids; Electron density; Explorer satellites; geomagnetic storm; Geomagnetic storms; ICON; Ion composition; Ionospheric effects; Latitude; lower middle latitudes; Magnetic storms; neutral wind; Plasma; Plasma density; Satellites; Strip; strip‐like bulge; topside ionosphere; Total Electron Content; Wind; Wind effects
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2022JA030541

During the geomagnetic storm on 3–6 November 2021, the in‐situ plasma density and the gridded total electron content (TEC) maps registered a persistent presence of the strip‐like bulges (electron density enhancement, also known as the shoulders in previous literatures) at lower‐middle latitudes. The observed strip‐like bulge resided in the Pacific‐America‐Atlantic sector and lasted from 07:00 UT on 4 November to 20:00 UT on 6 November. For the first time, the temporal evolution of the 2‐D strip‐like bulge was recorded by gridded TEC maps, though observations were limited over the North American continents. The TEC maps showed a continuous shrinking of the nightside midlatitude plasma band structure right before the presence of the narrow strip‐like bulge. Simultaneous measurements from the Ionospheric Connection Explorer satellite (ICON) revealed an equatorward turning of the field‐aligned ion transportation driven by the disturbance equatorward neutral winds. However, the enhanced fountain effect at low latitudes was not observed during the entire formation phase of the strip‐like bulge. We propose that the storm‐induced enhanced equatorward thermospheric neutral winds push the plasma equatorward along the field lines, and the plasma band structure was developed into the strip‐like bulge. In addition, the ion composition of both the plasma band structure and the strip‐like bulges are dominated by H+, and the maintenance of the strip‐like bulge could be due to the compensation of the downward plasmaspheric content flux. Key Points The temporal evolution of the 2‐D strip‐like bulge is recorded on gridded total electron content (TEC) maps The strip‐like bulge is a consequence of the narrowing midlatitude band structure driven by the disturbance neutral wind The enhanced equatorial fountain effect is not involved during the formation of the strip‐like bulge