地球磁层中合声波的频率与传播角分布特征
doi: 10.11728/cjss2024.06.2024-yg27 cstr: 32142.14.cjss.2024-yg27
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杨立贤 男, 2000年7月出生于广东省揭阳市, 现为长沙理工大学物理与电子科学学院硕士研究生, 主要研究方向为地球内磁层等离子体波动. E-mail: yang_lx@foxmail.com -
刘斯 女, 1984年出生于湖南省娄底市, 现为长沙理工大学物理与电子科学学院教授, 博士生导师, 主要研究方向为磁层物理. E-mail: liusi@csust.edu.cn
作者简介:
通讯作者:
Statistical Study on Propagation Characteristics of Chorus in the Earth’s Magnetosphere
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摘要: 合声波的频率和传播角是影响其与电子相互作用的关键参数. 2013年1月1日至2015年12月31日期间范艾伦卫星数据的统计分析结果表明, 在传播角θ≈35°处, 较强的合声波(>7×10–4 mV2·m–2·Hz–1)更倾向于出现在更窄的频率范围(0.3～0.4 fce). 随着磁壳数L的增大, θ≈35°处的合声波频谱变窄趋势逐渐明显. 从夜侧到晨侧(21:00 MLT－09:00 MLT), 较强的合声波能够在0.1～0.8 fce的频率范围内被观测到, 但夜侧θ≈35°处的合声波频谱宽度比晨侧更窄. 从上午到昏侧(09:00 MLT－21:00 MLT), 合声波电场功率谱密度明显降低, 且主要以斜传播(θ>60°)的下带合声波为主. 随着磁纬度λMLAT的增大, 上带合声波迅速减弱. 同时, θ≈35°处的下带合声波电场功率谱密度也逐渐下降. 本文揭示了不同区域内合声波强度的频率和传播角分布特征, 为构建更加精确的合声波–电子相互作用全球模型提供了重要信息.Abstract: The frequency and normal angle of chorus waves are the key parameters affecting its interaction with electrons. Statistical analysis of Van Allen satellite data from 1 January 2013 to 31 December 2015, indicates that the strong chorus waves (>7×10–4 mV2·m–2·Hz–1) tend to appear in a narrower frequency range (0.3～0.4 fce) at normal angle θ around 35°. As L increases, the trend of narrowing chorus wave spectrum at θ≈35° becomes more pronounced. From the night to the dawn (21:00 MLT－09:00 MLT), chorus waves can be observed within a frequency range of 0.1～0.8 fce, but the spectral width of chorus waves at θ≈35° on the nightside is narrower than that on the dawn. From the morning to the dusk (09:00 MLT－21:00 MLT), the electric power spectral density of chorus waves decreases significantly, mainly manifesting as lower band chorus waves with oblique propagation (θ>60°). With increasing magnetic latitude (λMLAT), the upper band chorus waves diminish rapidly, and the electric power spectral density of the lower band chorus waves at θ≈35° also gradually decreases. This study reveals the distribution characteristics of chorus wave intensity in terms of frequency and the normal angle in different regions, providing crucial information for constructing a more accurate global model of chorus wave-electron interactions.
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Key words:
- Radiation belts /
- Van Allen Probes /
- Statistical analysis /
- Chorus /
- Normal angle
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图 1 2013年5月7日范艾伦探测器-B观测到的合声波相关波谱数据
Figure 1. Van Allen Probe-B observation data on 7 May 2013
图 2 合声波的平均磁场(a)和电场(b)功率谱密度在θ-fn坐标系中的分布
Figure 2. Distribution of the average magnetic field (a) and electric field (b) power spectral density of the chorus in θ-fn coordinate
图 3 不同L范围内, 合声波电场功率谱密度在θ-fn坐标系中的分布
Figure 3. Distribution of the electric field power spectrum density of chorus in θ-fn coordinate within different L
图 4 不同MLT范围内合声波电场功率谱密度在θ-fn坐标系中的分布
Figure 4. Distribution of the electric field power spectrum density of chorus in θ-fn coordinate within different MLT
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