We investigate an equatorial plasma depletion (EPD) event in Japan near the early morning sector (04:30–7:30 LT) during the recovery phase of a geomagnetic storm occurred on Memorial weekend (May 28) 2017 by using multi-instrumental measurements, including ground-based Global Navigation Satellite Systems (GNSS) network, ionosonde stations, and space-based Swarm and Defense Meteorological Satellite Program (DMSP) missions. The detailed 2-D evolution of the early morning EPD is well observed using GNSS ROTI maps with high temporal-spatial resolution. Moreover, ROTI data from BeiDou Geostationary Earth Orbit satellites are used to detect the EPD signature for the first time. The dawn EPD signature was also observed at the topside ionosphere by in situ electron density (Ne) measurements and ROTI results by space-borne Swarm Alpha (A), Charlie (C), and DMSP F17 satellites, indicating that the equatorial depletions arose to higher altitudes. We suggest that both the eastward disturbance dynamo electric field and overshielding electric field near the early morning sector created a favorable condition for the growth of the Rayleigh–Taylor (R-T) instability, and thus result in the generation of the dawn EPD.

中文翻译：

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2017 年纪念周末风暴期间清晨赤道等离子体损耗的多仪器观测

我们使用多仪器测量调查了 2017 年纪念周末（5 月 28 日）发生地磁风暴恢复阶段在日本清晨扇区（04:30–7:30 LT）附近发生的赤道等离子体消耗 (EPD) 事件，包括地面全球导航卫星系统 (GNSS) 网络、电离探空仪站以及天基群和国防气象卫星计划 (DMSP) 任务。使用具有高时空分辨率的 GNSS ROTI 地图可以很好地观察到清晨 EPD 的详细二维演变。此外，来自北斗地球静止轨道卫星的 ROTI 数据首次用于检测 EPD 特征。通过原位电子密度 (Ne) 测量和星载 Swarm Alpha (A)、查理 (C)、和 DMSP F17 卫星，表明赤道损耗上升到更高的高度。我们认为，清晨扇区附近的东向扰动发电机电场和过屏蔽电场都为瑞利-泰勒（RT）不稳定性的增长创造了有利条件，从而导致黎明EPD的产生。