During the geomagnetic storm on September 8–9, 2017, shoulder‐like structures were persistently captured in the lower‐mid latitudes at multiple local times, by Swarm and DMSP satellite observations. A more telling terminology of such shoulder‐like structure called strip‐like bulge is proposed in this study, due to its global presence that spanning over 150° in longitude but only over 1°–5° in latitude. The strip‐like bulges can be categorized into sharp and blunt types depending on the sharpness of the density peaks. The blunt type was short‐lived and appeared earlier than the sharp type in the afternoon‐sunset sector. The sharp type was long‐lived and appeared at all the observed local times. Both two types of strip‐like bulges were dominated by the ion composition of the H⁺/He⁺, rather than O⁺. This is the first evidence that the plasmaspheric particles are involved in forming the ionospheric structure at such low latitude. Moreover, the equatorward movement of the bulges shared the same trends with the earthward movement of the plasmapause. These two types of strip‐like bulges showed different longitudinal dependencies controlled by the magnetic declination. We suggest that the combined effects from the plasmaspheric downwelling and disturbance neutral wind were responsible for the appearance of the strip‐like bulges.

中文翻译：

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在2017年9月8日至9日的共轭中低纬度地区持续发生带状等离子密度隆起

在2017年9月8日至9日的地磁风暴中，通过Swarm和DMSP卫星观测，在多个当地时间持续捕获了中低纬地区的肩状结构。这项研究提出了一种更具说服力的术语，称为肩带状隆起，这是由于其全球性存在，其经度跨度超过150°，而纬度仅跨度1°至5°。带状凸起可根据密度峰的锐度分为锐角和钝角两种类型。钝型是短命型的，并且比下午日落地区的锐型出现得早。尖锐类型寿命长，并且在所有观察到的当地时间都出现过。两种类型的条状凸起均由H ⁺ / He的离子组成决定⁺，而不是O ⁺。这是在如此低纬度下等离子层粒子参与形成电离层结构的第一个证据。此外，凸起的赤道运动与等离子暂停的向地球运动具有相同的趋势。这两种类型的条状凸起显示出不同的纵向相关性，这些相关性是由磁偏角控制的。我们认为等离子层下降和扰动中性风的综合作用是带状凸起的出现的原因。