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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >The ionospheric response to interplanetary magnetic field variations: Evidence for rapid global change and the role of preconditioning in the magnetosphere
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The ionospheric response to interplanetary magnetic field variations: Evidence for rapid global change and the role of preconditioning in the magnetosphere

机译：电离层对行星际磁场变化的响应：快速全球变化的证据以及磁层中预处理的作用

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摘要

We have found observational evidence for a rapid communication of interplanetary magnetic field (IMF) changes to the global ionosphere and evidence for the state of the magnetosphere in the previous hour conditioning this response. These conclusions are drawn from a case study of sunward flow bursts on the nightside polar cap boundary observed by geomagnetically conjugate HF radars. The flow burst excitation consists of two factors: (1) At the lime of the flow burst, the magnetosphere still held a memory of the stable and northward IMF period that had persisted up until 1 hour before the flow burst (internal condition). During the northward IMF period a theta aurora associated with a sunward how channel was formed in the polar cap. After that the IMF turned southward, and the transpolar are decayed antisunward. However, by the time of the flow burst (i.e., 1 hour after the IMF southward turning), the Sun-aligned are had not yet completely vanished, and in the poleward expanded portion of the northern plasma sheet, there was still a remnant of the sunward flow channel susceptive to an external forcing. (2) One hour after the southward turning of the IMF a sharp IMF transition from southward to northward B-Z impinged on the dayside magnetopause (external condition). On arriving at the dayside cusp ionosphere the B-Z transition signal pervaded the entire polar cap ionosphere instantaneously (<1 min) and reached the nightside plasma sheet. There, the remnant of the sunward flow channel was reactivated by the B-Z transition, and a sunward how burst was observed first in the northern ionosphere and then in the southern ionosphere with a 7-min time delay. Thus the sunward flow burst represents a rapid global response of the ionosphere starting 2-3 min after the IMF change at the subsolar magnetopause. [References: 45]
机译：我们发现了观测证据，证明行星际磁场（IMF）变化迅速传递到全球电离层，并且在前一小时调节了这一响应的磁层状态也得到了证据。这些结论是通过对地磁共轭高频雷达观测到的在夜间极性极帽边界上向阳流爆发的案例研究得出的。液流爆发激发由两个因素组成：（1）在液流爆发的时刻，磁层仍保留了一个稳定的，向北的IMF周期的记忆，该周期一直持续到液流爆发前1小时（内部条件）。在IMF向北的时期，theta极光与极光帽形成向阳通道有关。此后，国际货币基金组织转向南边，而跨极则向反方向衰变。但是，到水流爆发时（即IMF向南转弯1小时后），与太阳对齐的太阳尚未完全消失，并且在北部等离子板的极向扩展部分中，仍然残留着易受外界强迫的朝阳流道。 （2）IMF向南转一小时后，IMF从南向北B-Z急剧过渡，影响了白天的磁更年期（外部状况）。 B-Z跃迁到达白天的尖端电离层时，瞬时（<1分钟）遍及整个极地电离层，并到达了夜间的等离子体层。在那里，向阳流通道的残余物通过B-Z过渡而重新激活，并且向北向电离层首先观察到向阳的爆发方式，然后在南电离层中观察到了7分钟的时间延迟。因此，朝阳的水流爆发代表了IMF发生在日下磁层顶的2-3分钟后电离层的快速全局响应。 [参考：45]

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