Spatiotemporal Variability and Propagation of Equatorial Noise Observed by Cluster
Spatiotemporal Variability and Propagation of Equatorial Noise Observed by Cluster
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DOI：
10.1029/2001ja009159
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发表时间：
2002-12
影响因子：
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通讯作者：
O. Santolík;J. Pickett;D. Gurnett;M. Maksimović;N. Cornilleau-Wehrlin
中科院分区：
文献类型：
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作者：
O. Santolík;J. Pickett;D. Gurnett;M. Maksimović;N. Cornilleau-Wehrlin
我们报告了Cluster项目观测到的赤道电磁噪声的多点案例研究。高分辨率数据是在位于外层等离子层早晨区域的三个空间近距离点测量的。我们展示了辐射的窄纬度范围，典型宽度为2°，以最小b赤道附近为中心。不同卫星记录的功率谱显示出发射线的复杂结构，其相对强度和位置在1-2分钟的时间尺度和/或在几十个波长的空间尺度上变化。这些谱线与局部质子回旋加速器频率的谐波不匹配，因为如果波是由高能离子产生的，并且在源区域附近观察到，这是可以预期的。我们带来的观测证据表明，波传播具有显著的径向分量，因此可以从位于不同径向距离的遥远产生区域传播，其中离子回旋加速器频率与观测到的精细结构相匹配。
[1] We report a multipoint case study of the electromagnetic equatorial noise observed by the Cluster project. High-resolution data were measured in three close points in space located in the morning sector of the outer plasmasphere. We demonstrate a narrow latitudinal extent of the emissions with a typical width of 2°, centered near the minimum-B equator. Power spectra recorded by the different satellites show a complex structure of emission lines whose relative intensities and positions vary at timescales of 1–2 min and/or at spatial scales of tens of wavelengths. These lines do not match harmonics of the local proton cyclotron frequency, as it would be expected if the waves are generated by energetic ions and observed near the source region. We bring observational evidence that the waves propagate with a significant radial component and thus can propagate from a distant generation region located at different radial distances where ion cyclotron frequencies match the observed fine structure.