Off‐Equatorial Pi2 Pulsations Inside and Outside the Plasmapause Observed by the Arase Satellite
Off‐Equatorial Pi2 Pulsations Inside and Outside the Plasmapause Observed by the Arase Satellite
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Arase 卫星观测到的等离子层顶内外的离赤道 Pi2 脉动
DOI：
10.1029/2021ja029677
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Shnohara I.
中科院分区：
文献类型：
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作者：
Teramoto M.;Miyoshi Y.;Matsuoka A.;Kasahara Y.;Kumamoto A.;Tsuchiya F.;Nos? M.;Imajo S.;Shoji M.;Nakamura S.;Kitahara M.;Shnohara I.
利用2017年3月至2019年9月期间来自Arase卫星的磁场和电子密度数据，我们研究了Pi 2脉动在宽纬度范围内与等离子体顶相关的空间特性（绝对磁纬度，|MLAT|，< 45°）。当卫星处于午夜前扇区时，在低纬度地面站的夜侧，与南北（H）分量中的Pi 2脉动具有高相干性（> 0.7）的磁场扰动主要是从径向（BR）和压缩（BP）分量中的磁场中识别出来的。特别是，高相干BP事件分布在午夜前扇区的夜侧的宽L值和纬度范围内。我们利用Arase测量的电子密度确定了等离子体层顶的位置，发现在等离子体层顶附近，高相干事件的BP-H功率比和交叉相位分别呈现出一个逐渐的峰值和一个明显的相位变化，从0°到180°。这些特征表明，中纬度和低纬度的Pi 2脉动在夜面被激发的等离子体层虚拟共振模式。
Using magnetic field and electron density data from the Arase satellite for the period from March 2017 to September 2019, we investigate the spatial properties of Pi2 pulsations in relation to the plasmapause over a wide latitudinal range (absolute magnetic latitude, |Mlat|, < 45°) in the inner magnetosphere. Magnetic field disturbances that have high coherence (> 0.7) with Pi2 pulsations in the north‐south (H) component at low‐latitude ground stations on the nightside, are dominantly identified from the magnetic fields in the radial (BR) and compressional (BP) components when the satellite is in the pre‐midnight sector. In particular, high‐coherenceBPevents are distributed over wideL‐values and latitudinal ranges on the nightside in the pre‐midnight sector. We identify the location of the plasmapause using the electron densities measured by Arase, and found that theBP‐Hpower ratio and the cross phases of the high‐coherence events show a gradual peak and a clear phase change from 0° to 180° in the vicinity of the plasmapause, respectively. These features indicate that mid‐ and low‐latitude Pi2 pulsations on the nightside are excited by the plasmaspheric virtual resonance mode.