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Low Frequency ULF Waves in the Earth's Inner Magnetosphere: Statistics During Coronal Mass Ejections and Seeding of EMIC Waves
Journal of Geophysical Research: Space Physics ( IF 2.8 ) Pub Date : 2021-07-19 , DOI: 10.1029/2021ja029247
Konstantin V. Gamayunov 1 , Mark J. Engebretson 2
Affiliation  

Here we perform a statistical analysis of low frequency ultra-low-frequency (ULF) waves (urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0001 mHz - Hz) in the Earth's inner magnetosphere excluding electromagnetic ion cyclotron waves concurrently observed. We use the magnetic field data from the two Van Allen Probes during their first magnetic local time (MLT) revolution that cover the periods of coronal mass ejections. The major results of our analysis are as follows. (a) Spectra of both the transverse and compressional ULF waves are well approximated by the power-laws in the urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0002 mHz - Hz frequency range. (b) There are two sources of the low frequency ULF waves: an internal magnetospheric source and an external source outside of the magnetosphere. (c) The average transverse power in the 6–24 h MLT sector dominates that in the 0–6 h sector, whereas the compressional power in the 12–24 h sector dominates that in the 0–12 h sector. (d) The average powers of transverse and compressional ULF waves in the plasmasphere dominate the average powers in the high L shell region of urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0003, and there is a deep power minimum in the intermediary region of urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0004. (e) The compressional ULF wave power has a maximum in the near equatorial region, whereas the transverse power has a minimum there. (f) A wave energy cascade from low frequency ULF waves into the higher frequency range of EMIC waves (urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0005 Hz) supplies the nonthermal seed fluctuations from which EMIC waves can then grow due to instabilities of the energetic magnetospheric ions.

中文翻译:

地球内部磁层中的低频 ULF 波:日冕物质抛射和 EMIC 波播种期间的统计数据

在这里,我们urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0001对地球内部磁层中的低频超低频 (ULF) 波 ( mHz - Hz)进行了统计分析,不包括同时观察到的电磁离子回旋波。我们使用了两个范艾伦探测器在第一次磁本地时间 (MLT) 旋转期间的磁场数据,这些数据涵盖了日冕物质抛射的时期。我们的主要分析结果如下。(a) 横波和纵波 ULF 波的频谱都可以通过幂律很好地近似urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0002mHz - Hz 频率范围。(b) 低频超低频波有两个来源:内部磁层源和磁层外的外部源。(c) 6-24 h MLT 扇区的平均横向功率在 0-6 h 扇区中占主导地位,而 12-24 h 扇区中的压缩功率在 0-12 h 扇区中占主导地位。(d) 等离子层中横向和压缩 ULF 波的平均功率在 的高 L 壳区域中占主导地位urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0003,并且在 的中间区域有一个深功率最小值骨灰盒:x-wiley:21699380:媒体:jgra56626:jgra56626-math-0004。(e) 压缩超低频波功率在近赤道区域最大,而横向功率在那里最小。(f) 从低频 ULF 波到 EMIC 波的高频范围的波能量级联(urn:x-wiley:21699380:media:jgra56626:jgra56626-math-0005 Hz) 提供非热种子波动,然后由于高能磁层离子的不稳定性,EMIC 波可以从中生长。
更新日期:2021-08-09
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