Storm Time Electrified MSTIDs Observed Over Mid‐Latitude North America
Storm Time Electrified MSTIDs Observed Over Mid‐Latitude North America
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DOI：
10.1029/2022ja031115
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
I. J. Kelley;B. Kunduri;J. Baker;J. Ruohoniemi;S. Shepherd
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作者：
I. J. Kelley;B. Kunduri;J. Baker;J. Ruohoniemi;S. Shepherd
中尺度电离层移动扰动（MSTID）是中纬度电离层的突出和普遍存在的特征，并在超级双极光雷达网（SuperDARN）和高分辨率全球导航卫星服务（GNSS）总电子含量（TEC）数据中观测到。驱动这些MSTID的机制是一个开放的研究领域，特别是在磁暴期间。以前的研究表明，夜侧MSTID与像帕金斯这样的电动力学不稳定机制有关，特别是在地磁安静条件下。然而，昼侧MSTID往往与大气重力波。很少有研究分析了中纬度强磁暴期间驱动MSTID的机制。在这项研究中，我们介绍了在2017年9月7日至8日的磁暴期间（峰值Kp达到9），在北美地区的GNSS TEC数据和SuperDARN雷达中观测到的中纬度MSTID。在SuperDARN中，在电离层后向散射中观测到MSTID，其视线速度超过800 m/s。此外，当MSTID通过视场时，雷达LOS速度以达到±500 m/s的幅度振荡。在去趋势TEC中，这些MSTID产生的扰动达到背景TEC幅度的50%。观测到MSTID在向西/西南方向传播，传播时间为15 min。沿沿着SuperDARN波束投影去趋势GNSS TEC数据表明，TEC的增强与SuperDARN SNR和正LOS速度的增强相关。最后，SuperDARN LOS速度系统性地在MSTID的波峰和波谷之间切换极性，表明在这些MSTID期间存在极化电场和电动不稳定过程。
Medium‐scale Traveling Ionospheric Disturbances (MSTIDs) are prominent and ubiquitous features of the mid‐latitude ionosphere, and are observed in Super Dual Auroral Radar Network (SuperDARN) and high‐resolution Global Navigational Satellite Service (GNSS) Total Electron Content (TEC) data. The mechanisms driving these MSTIDs are an open area of research, especially during geomagnetic storms. Previous studies have demonstrated that nightside MSTIDs are associated with an electrodynamic instability mechanism like Perkins, especially during geomagnetically quiet conditions. However, dayside MSTIDs are often associated with atmospheric gravity waves. Very few studies have analyzed the mechanisms driving MSTIDs during strong geomagnetic storms at mid‐latitudes. In this study, we present mid‐latitude MSTIDs observed in de‐trended GNSS TEC data and SuperDARN radars over the North American sector, during a geomagnetic storm (peak Kp reaching 9) on 7–8 September 2017. In SuperDARN, MSTIDs were observed in ionospheric backscatter with Line of Sight (LOS) velocities exceeding 800 m/s. Additionally, radar LOS velocities oscillated with amplitudes reaching ±500 m/s as the MSTIDs passed through the fields‐of‐view. In detrended TEC, these MSTIDs produced perturbations reaching ∼50 percent of background TEC magnitude. The MSTIDs were observed to propagate in the westward/south‐westward direction with a time period of ∼15 min. Projecting de‐trended GNSS TEC data along SuperDARN beams showed that enhancements in TEC were correlated with enhancements in SuperDARN SNR and positive LOS velocities. Finally, SuperDARN LOS velocities systematically switched polarities between the crests and the troughs of the MSTIDs, indicating the presence of polarization electric fields and an electrodynamic instability process during these MSTIDs.