An eastward propagating compressional Pc 5 wave observed by AMPTE/CCE in the postmidnight sector. [Active Magnetospheric Particle Tracer Explorers
An eastward propagating compressional Pc 5 wave observed by AMPTE/CCE in the postmidnight sector. [Active Magnetospheric Particle Tracer Explorers
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DOI：
10.1029/ja092ia12p13472
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发表时间：
1987-12
期刊：
影响因子：
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通讯作者：
Kazue Takahashi;R. Mcentire;L. Zanetti;R. Lopez;L. Kistler
中科院分区：
文献类型：
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作者：
Kazue Takahashi;R. Mcentire;L. Zanetti;R. Lopez;L. Kistler
来自三个仪器的数据，磁力计，电荷能量质谱仪，和中等能量粒子，主动磁层粒子示踪探测器/电荷成分探测器（CCE）航天器上的一个分析器已被用来研究在202天（7月21日）1925-2200 UT观测到的一个压缩Pc 5波1986年10月10日，在小地磁活动开始附近的午夜后扇区，径向距离为1.8RE。该波表现出谐波相关的横向和压缩磁振荡，调制中能质子（E = 10 keV）的通量，和一个大的方位波数（m = 65）。这些性质与以前在地球静止轨道上观测到的压缩Pc 5波的性质相似。与CCE事件相关的独特观测是发生在午夜后的扇区，相对于航天器的向东（或向日）传播，以及扰动磁场的左手极化。这与以前的地球同步观测相反。我们建议，独特的传播和极化所造成的黎明到黄昏的直流电场对流等离子体向阳。在等离子体静止坐标系中可能向西传播的波，由于电场漂移速度大于波的相速度，因此似乎向东传播到观察者。
Data from three instruments, the magnetometer, the charge-energy-mass spectrometer, and the medium-energy particle, analyzer onboard the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (CCE) spacecraft have been used to study a compressional Pc 5 wave observed at 1925–2200 UT on day 202 (July 21) of 1986 at a radial distance of ≃8 RE in the postmidnight sector near the beginning of minor geomagnetic activity. The wave exhibited harmonically related transverse and compressional magnetic oscillations, modulation of the flux of medium energy protons (E ≳ 10 keV), and a large azimuthal wave number (m ∼ 65). These properties are similar to those of compressional Pc5 waves observed previously at geostationary orbit. The unique observations associated with the CCE event are the occurrence in the postmidnight sector, the eastward (or sunward) propagation with respect to the spacecraft, and the left-handed polarization of the perturbed magnetic field. These are opposite to previous geostationary observations. We propose that the unique propagation and polarization are caused by a dawn-to-dusk dc electric field which convects the plasma sunward. The wave, probably propagating westward in the plasma rest frame, appears to propagate eastward to the observer because the electric field drift velocity is larger than the wave phase velocity.