Localization of auroral Langmuir turbulence in thin layers
Localization of auroral Langmuir turbulence in thin layers
复制标题
薄层中极光朗缪尔湍流的定位
DOI：
10.1002/jgra.50314
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
J. Labelle
中科院分区：
文献类型：
--
作者：
H. Akbari;J. Semeter;M. Nicolls;M. Broughton;J. Labelle
最近发现的相干回波的扑克平坦非相干散射雷达数据与平坦的离子线频谱和同时双峰等离子体线频谱在低电离层F区域进行了更详细的研究。高距离分辨率测量显示，湍流有时表现为两个分离约50公里的并发层。湍流层出现在零电子密度梯度的区域，支持传播效应在限制波的振幅方面发挥重要作用的解释。虽然朗缪尔强度受到层外传播效应的限制，但它在层内达到非线性状态，从而导致观察到的范围和光谱形态。此外，静电波的雷达测量似乎在空间和时间上与自然极光电磁辐射相关，支持先前的理论，即“MF-爆发”是由顶部F区域的软电子沉淀（~几百电子伏）产生的朗缪尔波的线性转换产生的。本报告中的结果表明，所观察到的朗缪尔湍流和MF-爆发都是同一过程的表现。
The recently discovered coherent echoes in the Poker Flat Incoherent Scatter Radar data with flat ion‐line spectrum and simultaneous double‐peaked plasma‐line spectrum in the lower ionospheric F region are investigated in greater detail. High‐range resolution measurements reveal that the turbulence is sometimes manifested as two concurrent layers separated by about 50 km. The turbulence layers appear at regions of zero electron density gradient, supporting the interpretation that propagation effects play an important role in limiting the waves’ amplitude. Although Langmuir intensity is limited by propagation effects outside of the layers, it reaches to nonlinear regime inside the layers, giving rise to the observed range and spectral morphologies. Furthermore, the radar measurements of the electrostatic waves appear to be correlated in space and time with natural auroral electromagnetic emissions, supporting the previous theory that “MF‐bursts” are produced by linear conversion of Langmuir waves produced by soft electron precipitation (~few hundred electronvolts) on the topside F region. The results presented in this report suggest that the observed Langmuir turbulence and MF‐burst are both manifestations of the same process.