Rocket Observation of Sub‐Relativistic Electrons in the Quiet Dayside Auroral Ionosphere
Rocket Observation of Sub‐Relativistic Electrons in the Quiet Dayside Auroral Ionosphere
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DOI：
10.1029/2020ja028633
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发表时间：
2021-06
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通讯作者：
T. Namekawa;T. Mitani;K. Asamura;Y. Miyoshi;K. Hosokawa;Y. Ogawa;S. Saito;T. Hori;S. Sugo;O. Kawashima;S. Kasahara;R. Nomura;N. Yagi;M. Fukizawa;T. Sakanoi;Y. Saito;A. Matsuoka;I. Shinohara;Y. Fedorenko;A. Nikitenko;C. Koehler
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作者：
T. Namekawa;T. Mitani;K. Asamura;Y. Miyoshi;K. Hosokawa;Y. Ogawa;S. Saito;T. Hori;S. Sugo;O. Kawashima;S. Kasahara;R. Nomura;N. Yagi;M. Fukizawa;T. Sakanoi;Y. Saito;A. Matsuoka;I. Shinohara;Y. Fedorenko;A. Nikitenko;C. Koehler
在地磁平静条件下（AE ≤ 100 nT，Kp = 1-），观测到180 - 550 keV的电子能谱沉淀到向阳侧极区电离层。观测是在73-184公里的高度由RockSat‐XN探空火箭上的HEP仪器进行的，该火箭已从挪威安岛发射。观测到的沉淀电子的能谱遵循−4.9 ± 0.4的幂律，并且电子通量在观测期间（274.4 s）变化不大。俄罗斯Lovozero附近的地基VLF接收器观测显示，在火箭观测期间存在哨声波活动。在RockSat‐XN观测前几分钟，POES 18/MEPED观测到沉淀电子，这也表明在靠近火箭轨道的位置有哨声模式的合唱波活动。利用位于黄昏的Arase卫星的数据作为初始条件，对波粒相互作用进行了试验粒子模拟。模拟结果表明，哨声模波可以与高纬度的亚相对论电子共振。这些结果表明，RockSat‐XN观测到的降水可能是由哨声波和亚相对论电子之间的波粒相互作用引起的。
An energy spectrum of electrons from 180 to 550 keV precipitating into the dayside polar ionosphere was observed under a geomagnetically quiet condition (AE ≤ 100 nT, Kp = 1‐). The observation was carried out at 73–184 km altitudes by the HEP instrument onboard the RockSat‐XN sounding rocket that has been launched from Andøya, Norway. The observed energy spectrum of precipitating electrons follows a power law of −4.9 ± 0.4 and the electron flux does not vary much over the observation period (∼274.4 s). A nearby ground‐based VLF receiver observation at Lovozero, Russia shows the presence of whistler‐mode wave activities during the rocket observation. A few minutes before the RockSat‐XN observation, POES18/MEPED observed precipitating electrons, which also suggest whistler‐mode chorus wave activities at the location close to the rocket trajectory. A test‐particle simulation for wave‐particle interactions was carried out using the data of the Arase satellite as the initial condition which was located on the duskside. The result of the simulation shows that whistler‐mode waves can resonate with sub‐relativistic electrons at high latitudes. These results suggest that the precipitation observed by RockSat‐XN is likely to be caused by the wave‐particle interactions between whistler‐mode waves and sub‐relativistic electrons.