【摘要】 本文利用射线跟踪技术研究了电离层赤道异常区内地面哨声非导管传播的可能性。考察了负电离纬向梯度对非导管哨声传播的影响,并检验了哨声射线路径参数和群时延对频率的依赖关系。计算结果证明,夜间在赤道异常区内的电离层中,存在一些地面可检测哨声的非导管传播通道;沿位于通道内的射线路径传播的哨声波,透出电离层后,可同时激发电离层—地面波导的朝极和朝赤道方向传播;在磁纬10°附近,到达共轭电离层底部的射线有明显的“聚焦”效应。本文结果比较满意地解释了近年来在我国南部地区地面台网(磁纬19.4°N至5.5°N)同时观测到的一部分哨声的传播特征。更多还原

【Abstract】 In this paper, ray-tracing computations are carried out to study the propagation mechanism of nighttime whistlers simultaneously observed in four ground stations of South China (Wuchang, geomagnetic Lat. 19.4°N; Zhanjiang, 10°N; Yulin, 7°N; Yong-xing Island, 5.5°N). In the computations a field aligned diffusive equilibrium model for electron-ion density distribution in ionosphere has been used, and a suitable negative latitudinal gradient of ionization associated with the equatorial anomaly has also been taken into account. It is found that in the ionospheric region with geomagnetic latitudes below 20° there exist some nonducted propagation channels of whistler mode waves detectable on the ground. The effects of different wave frequencies and different initial wave normals on the path parameters and whistler dispersion have been examined. The results of present paper can satisfactorily explain the propagation characteristics of some whistlers simultaneously observed in the ground station network mentioned above.更多还原