Interpretation of HF radar ionospheric Doppler spectra by collective wave scattering theory
Interpretation of HF radar ionospheric Doppler spectra by collective wave scattering theory
复制标题
集体波散射理论解释高频雷达电离层多普勒频谱
DOI：
10.1007/s00585-997-0692-z
复制
发表时间：
1993
影响因子：
1.9
通讯作者：
K. Baker
中科院分区：
文献类型：
--
作者：
C. Hanuise;J. Villain;D. Grésillon;B. Cabrit;R. Greenwald;K. Baker
根据非均匀等离子体对集体波的散射理论，流体运动谱既可以是由于速度色散引起的高斯多普勒谱，也可以是当散射波长大于速度涨落的相关长度时的洛伦兹谱。SHERPA高频相干雷达探测高纬度电离层中8至20米波长的密度波动，其数据中有这两类多普勒频谱。大多数自相关函数最适合指数形状，对应于洛伦兹多普勒频谱。然而，高斯形状的拟合有时更好。这两个频谱形状中的每一个都与当地电离层参数的值有关。我们提出了相关时间和相关长度的波的初步测量，并总结了地球物理研究的谱宽的意义
According to the theory of collective wave scattering by a non-uniform plasma, the fluid motion spectrum can be either the Gaussian Doppler spectrum due to velocity dispersion, or a Lorentzian spectrum when the scattering wavelength becomes longer than the correlation length of velocity fluctuations. These two types of Doppler spectra are present in data from the SHERPA HF coherent radar, which detects 8 to 20-m wavelength density fluctuations in the high-latitude ionosphere. Most autocorrelation functions are best fitted to an exponential shape, corresponding to a Lorentzian Doppler spectrum. Nevertheless, the fit is sometimes better for a Gaussian shape. Each of the two spectral shapes is related to values of the local ionospheric parameters. We present preliminary measurements of the correlation time and correlation length of the waves, and concluding remarks on the significance of spectral widths for geophysical studies