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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Roles of Flow Braking, Plasmaspheric Virtual Resonances, and Ionospheric Currents in Producing Ground Pi2 Pulsations
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Roles of Flow Braking, Plasmaspheric Virtual Resonances, and Ionospheric Currents in Producing Ground Pi2 Pulsations

机译:制动,Plasmaspheric虚拟角色的流共振,电离层电流产生地面Pi2脉动

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摘要

In one model, Pi2 pulsations are driven pulse by pulse by fast mode pulses that are launched as periodic bursty bulk flows brake when they approach the Earth. We have examined this model by analyzing data from multiple spacecraft and ground magnetometers for a Pi2 pulsation event. During the event, which started at ~2226 UT on 8 November 2014, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-D detected an ~2-min-period plasma bulk flow oscillation in the near-Earth magnetotail, while THEMIS-E and Van Allen Probes-B, both located on the nightside just earthward of the electron plasmapause, detected a Pi2 pulsation consisting of a 10-mHz oscillation in the azimuthal component of the electric field and a 19-mHz oscillation in the compressional component of the magnetic field. On the ground, magnetic field oscillations containing both frequencies were observed both on the nightside and on the dayside. The nightside observations indicated that the pulsation had a radially standing structure, which is consistent with plasmaspheric virtual resonances (PVRs) excited in a magnetohydrodynamic simulation assuming an impulsive energy source. Cross-spectral analysis of the magnetotail flow oscillation and the Pi2 pulsation indicated low coherence between them. These results suggest that the flow oscillation contributed to the Pi2 pulsation as a broadband energy source and that only the spectral components matching the PVR frequencies were detected with well-defined frequencies. Ionospheric currents connected to the PVRs may be responsible for the appearance of the pulsation on the dayside.
机译:在一个模型中,皮脉动驱动脉冲快速模式脉冲发射的脉冲周期性丛发性散装流制动时接近地球。通过分析从多个航天器和数据地面磁力计Pi2脉动事件。在活动期间,开始在8 ~ 2226 UT2014年11月,事件和时间的历史宏观尺度的相互作用,在亚暴(裁判)- d检测到一个~ 2-min-period等离子体体积在近地磁尾流动振荡,尽管THEMIS-E和范艾伦Probes-B,两者兼而有之位于阴面的向地面电子等离子体层顶,发现皮脉动组成的10 mhz的振荡电场和方位的组成部分在压缩组件19-mHz振荡的磁场。字段包含两个频率振荡观察在阴面,在吗的光面。脉动有径向站结构,与plasmaspheric一致在一个虚拟的共鸣(个人)兴奋磁流体动力模拟假设一个冲动的能量来源。磁尾流的振荡和皮脉动表示低相干。这些结果表明,流动振荡导致了Pi2脉动作为宽带能源,只有光谱组件匹配PVR的频率发现与定义的频率。电离层电流连接到个人负责脉动的外观的光面。

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