穿过电离层电子密度不均匀体的脉冲平均到达时间

Mean Arrival Time of Pulse Signal Propagating Through Ionospheric Irregularities

本文利用前向多重散射理论的新进展，推导了穿过电离层电子密度不均匀体脉冲平均到达时间的理论计算公式，其中包括背景介质折射效应的贡献、色散效应的贡献、电离层电子密度不均匀体的散射效应的贡献和色散效应的贡献。在水平分层背景电离层和高频近似的情况下，给出了背景电离层折射效应、一阶色散效应、电子密度不均匀体的散射效应和一阶色散效应对对称脉冲平均到达时间影响的计算公式。针对特定的电离层情况，分别计算了上述几种电离层效应对脉冲平均到达时间的影响，着重研究了散射对脉冲平均到达时间的影响随不均匀体谱指数、内尺度、外尺度和电子密度相对起伏方差的变化。结果表明，在某些情况下电子密度不均匀体散射对脉冲平均到达时间的影响相对于背景电离层的影响是非常重要的，在工程应用中必须加以考虑。

Based on new advance in the multiple forward scattering theory of radio propagation in a random meidum, formula are derived for the study of mean arrival time of pulse signal propagating through the ionospheric irregularities, which takes into account of the refractive and dispersive effects of the background ionosphere on the mean arrival time ,and of the multiple scattering and dispersive effects of the ionospheric electron density irregularities embeded in the background ionosphere. Under high-freqency approximation and asumption of a horizontally stratified background ionosphere, formula are given for calculating the refractive effect of the background ionosphere,the first order dispersive effect of the background ionosphere,the multiple forward scattering effect of the ionospheric electron density irregularities and its first order dispersive effect on the mean arrival time.With a specified background ionosphere,above ionospheric effects on the mean arrival time are studied with emphesis to variations of the scattering effect with the spectrum index ,inner size and outer size of irrgularities. Results demonstrate that the scattering effect of irregularities is relatively important with respect to the refractive effect of the background ionosphere in certain cases, and that it is must taken into account in practical applications.