Analysis of fine ELF wave structures observed poleward from the ionospheric trough by the low‐altitude satellite DEMETER
Analysis of fine ELF wave structures observed poleward from the ionospheric trough by the low‐altitude satellite DEMETER
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DOI：
10.1002/2013ja019557
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发表时间：
2014-03
期刊：
影响因子：
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通讯作者：
M. Parrot;F. Němec;O. Santolík
中科院分区：
文献类型：
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作者：
M. Parrot;F. Němec;O. Santolík
DEMETER 是一艘三轴稳定地球指向航天器，于 2004 年 6 月 29 日发射进入低空（710 公里）极圆轨道，随后降至 650 公里，直到 2010 年 12 月任务结束。DEMETER 测量了地球周围除磁不变纬度 >65° 以外的电磁波。电场的频率范围为直流至 3.5 MHz，磁场的频率范围为几赫兹至 20 kHz。 DEMETER 之前曾在高磁活动期间在电离层槽附近观测到电磁离子回旋 (EMIC) 波，本文描述了另一种类型的 EMIC 波。这些波也在波谷附近观察到，但它们向极地延伸，波谷充当边界。它们仅在夜间观测到，并且优先在地磁亚暴期间观测到。波传播的分析表明，它们几乎沿着环境磁场传播，并且来自较大的径向距离。
DEMETER was a three‐axis stabilized Earth‐pointing spacecraft launched on 29 June 2004 into a low‐altitude (710 km) polar and circular orbit that was subsequently lowered to 650 km until the end of the mission in December 2010. DEMETER measured electromagnetic waves all around the Earth except at magnetic invariant latitudes >65°. The frequency range for the electric field was from DC up to 3.5 MHz and for the magnetic field from a few hertz up to 20 kHz. Electromagnetic ion cyclotron (EMIC) waves have been previously observed by DEMETER close to the ionospheric trough during high magnetic activity, and this paper describes another type of EMIC waves. These waves are also observed close to the trough, but they extend poleward, with the trough acting as a boundary. They are observed exclusively during the night and preferentially during geomagnetic substorms. The analysis of wave propagation shows that they propagate nearly along the ambient magnetic field and that they come from larger radial distances.