Periodic Modulation of the Upper Ionosphere by ULF Waves as Observed Simultaneously by SuperDARN Radars and GPS/TEC Technique
Periodic Modulation of the Upper Ionosphere by ULF Waves as Observed Simultaneously by SuperDARN Radars and GPS/TEC Technique
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DOI：
10.1029/2020ja028032
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发表时间：
2020-07
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通讯作者：
O. Kozyreva;V. Pilipenko;E. Bland;L. Baddeley;V. I. Zakharov
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文献类型：
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作者：
O. Kozyreva;V. Pilipenko;E. Bland;L. Baddeley;V. I. Zakharov
最近的工作表明，地面磁力计观测到的全球Pc 5脉动可能伴随着GPS接收器测量的电离层总电子含量（TEC）的周期性振荡。这些TEC观测可能为磁层-电离层耦合机制提供新的见解，特别是当与其他地面观测技术相结合时。本文介绍的是一个大规模的早晨扇区Pc 5事件，该事件由地面磁力计，两个高频超级双极光雷达网（SuperDARN）雷达和几个全球定位系统（GPS）/TEC接收器同时观测。地面磁力计和雷达观测到的2.6 mHz瞬态脉动伴随着TEC（ROT）时间变化率在相同频率下的周期性波动。为了研究超低频（ULF）波对TEC调制的可能机制，我们确定了磁、电离层多普勒速度和ROT振荡的频谱振幅之间的比值。同时磁场和电离层多普勒速度振荡之间的关系可以合理地解释使用阿尔芬波与薄电离层相互作用的理论。尽管观测到的ROT和多普勒速度振幅之间的比率可以通过极光纬度顶部电离层等离子体局部陡峭梯度的出现来解释，但不能认为负责的调制机制已经牢固确立。
Recent work has demonstrated that global Pc5 pulsations observed by ground‐based magnetometers may be accompanied by periodic oscillations in the total electron content (TEC) of the ionosphere measured by GPS receivers. These TEC observations may provide new insights into magnetosphere‐ionosphere coupling mechanisms, especially when combined with other ground‐based observational techniques. Presented in this paper is a large‐scale morning sector Pc5 event which was observed simultaneously by ground‐based magnetometers, two high‐frequency Super Dual Auroral Radar Network (SuperDARN) radars, and several Global Positioning System (GPS)/TEC receivers. The transient 2.6 mHz pulsations observed by the ground magnetometers and radars are accompanied by periodic fluctuations in the time rate‐of‐change of TEC (ROT) at the same frequency. To investigate possible mechanisms for the TEC modulation by ultralow frequency (ULF) waves, we determine the ratios between the spectral amplitudes of the magnetic, ionospheric Doppler velocity and ROT oscillations. The relationship between the simultaneous magnetic field and ionospheric Doppler velocity oscillations can be reasonably well interpreted using the theory of Alfven wave interaction with the thin ionospheric layer. Though the observed ratio between ROT and Doppler velocity amplitudes can be explained by the occurrence of local steep gradient of the topside ionosphere plasma at auroral latitudes, the responsible modulation mechanism cannot be considered as firmly established.