Ionospheric Plasma Density Oscillation Related to EMIC Pc1 Waves
Ionospheric Plasma Density Oscillation Related to EMIC Pc1 Waves
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DOI：
10.1029/2020gl089000
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发表时间：
2020-08
影响因子：
5.2
通讯作者：
Hyangpyo Kim;K. Shiokawa;Jaeheung Park;Y. Miyoshi;Y. Miyashita;C. Stolle;Khan‐Hyuk Kim;J. Matzka;S. Buchert;T. Fromm;J. Hwang
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文献类型：
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作者：
Hyangpyo Kim;K. Shiokawa;Jaeheung Park;Y. Miyoshi;Y. Miyashita;C. Stolle;Khan‐Hyuk Kim;J. Matzka;S. Buchert;T. Fromm;J. Hwang
我们报告的等离子体密度振荡相干磁Pc 1波的第一次观察。Swarm卫星观测到0.5-3 Hz波段的压缩Pc 1波活动，这与现场等离子体密度振荡是一致的。在Pc 1事件位置附近，南极Neumayer站III（L ~ 4.2）在水平分量中记录了类似的Pc 1事件，而NOAA-15观测到能量超过30 keV的孤立质子沉淀。所有这些观测结果都支持Swarm上的压缩Pc 1波是由来自磁层的电磁离子回旋（EMIC）波转换而来的振荡。磁场和等离子体密度同相振荡。我们比较了归一化到背景值的密度振荡和磁场振荡的振幅，发现密度功率远大于磁场功率。这种差异不能用简单的磁流体动力学（MHD）模型来解释，尽管背景电离层密度的陡峭水平/垂直梯度可以部分地调和这种差异。
We report the first observation of plasma density oscillations coherent with magnetic Pc1 waves. Swarm satellites observed compressional Pc1 wave activity in the 0.5–3 Hz band, which was coherent with in situ plasma density oscillations. Around the Pc1 event location, the Antarctic Neumayer Station III (L ~ 4.2) recorded similar Pc1 events in the horizontal component while NOAA‐15 observed isolated proton precipitations at energies above 30 keV. All these observations support that the compressional Pc1 waves at Swarm are oscillations converted from electromagnetic ion cyclotron (EMIC) waves coming from the magnetosphere. The magnetic field and plasma density oscillate in‐phase. We compared the amplitudes of density and magnetic field oscillations normalized to background values and found that the density power is much larger than the magnetic field power. This difference cannot be explained by a simple magnetohydrodynamic (MHD) model, although steep horizontal/vertical gradients of background ionospheric density can partly reconcile the discrepancy.