Interpreting observations of MF/HF radio emissions: Unstable wave modes and possibilities to passively diagnose ionospheric densities
Interpreting observations of MF/HF radio emissions: Unstable wave modes and possibilities to passively diagnose ionospheric densities
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解释中频/高频无线电发射的观测结果：不稳定的波模式和被动诊断电离层密度的可能性
DOI：
10.1029/2001ja000315
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发表时间：
2002
影响因子：
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通讯作者：
J. Labelle
中科院分区：
文献类型：
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作者：
A. Weatherwax;P. Yoon;J. Labelle
[1]Wind航天器最近的卫星观测以及ISIS 1号和2号卫星早些时候对中频/高频无线电发射的观测都归因于在顶侧电离层中产生的上混合/Z模式波，其频率是当地电子陀螺频率fce的两到三倍。我们计算的增长率的各种波模式的高度在顶侧电离层和各种电子密度分布的函数，采用修改后的损失锥/马蹄形电子分布函数作为自由能源的排放。这些计算代表了这种不稳定性模型的顶侧电离层的第一个应用程序，在平行于早期的努力，涉及波激发在F区域的底侧。除了已知在上混合频率与回旋加速器谐波匹配的点处不稳定的Z模式之外，对于某些密度分布，可以在电子回旋加速器频率的第一谐波附近直接产生X模式。我们进一步提出了如何将这些排放可能被用作电离层等离子体特性的远程诊断。
[1] Recent satellite observations by the Wind spacecraft, as well as earlier observations by the ISIS 1 and 2 satellites, of MF/HF radio emissions have been attributed to upper hybrid/Z mode waves generated in the topside ionosphere at two and three times the local electron gyrofrequency fce. We calculate the growth rates of such emissions for various wave modes as a function of altitude in the topside ionosphere and for a variety of electron density profiles, employing a modified loss-cone/horseshoe electron distribution function as the free energy source. These calculations represent the first application of this instability model to the topside ionosphere, in parallel to earlier efforts involving wave excitation in the bottomside of the F region. In addition to the Z mode, which is known to be unstable at points where the upper hybrid frequency matches cyclotron harmonics, the X mode can be directly generated near the first harmonic of the electron cyclotron frequency for certain density profiles. We further put forth how these emissions might be used as a remote diagnostic of ionospheric plasma properties.
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