典型电离层多普勒记录及其讨论

SOME TYPICAL RECORDS OF IONOSPHERIC DOPPLER SHIFT AND THEIR SIGNIFICANCE IN THE STUDY OF IONOSPHERIC MORPHOLOGY

由于地面电离层多普勒频率偏移测量具有时间连续、设备相对简便等固有特征,它特别适合于扰动监测.本文在整理北京大学电离层高频多普勒台站观测资料的基础上,给出了一些典型电离层多普勒效应观测现象,这些现象反映了多普勒频移对电离层Es,声重波,不规则结构及耀斑引起的突然扰动等的响应,表明多普勒资料的细致分析对电离层形态学研究有其特殊意义.利用IRI模型,对多普勒频移的太阳耀斑效应及电离层不规则结构对多普勒频移的影响进行了模拟计算,理论结果与观测基本一致,从而大体上解释了这些响应的物理机制.论文最后对观测到的一种特殊的记录类型——S型描迹的具体成因作了详细的分析和讨论,指出在一定条件下,以一定相位速度水平传播的声重波可以产生这类记录,给出了相位速度和振幅等声重波参数与记录描迹形状的关系,这对从多普勒频移记录推演电离层中的波动特征有一定的帮助.

The measurements of HF Doppler shift in the ionosphere have long been a powerful tool in monitoring the ionospheric disturbances due to its features of continuity in time and simplicity. In this paper, based on the analysis of data from the HF Doppler station at Peking University, some typical records with special morphological characteristics of the ionosphere were shown. These records are recognized as the manifestations of sporadic-E, irregularities, acoustic-gravity waves in different scales and response to the sudden change of electron density due to solar flares. Using IRI model of the ionosphere, responses of Doppler shift to solar flare and ionospheric irregularities are simulated. The results are in agreements with observations so that the mechanics of such physical processes are explained. A special kind ofrecords——'S' shaped trace is introduced and programs designed to simulate suchrecords. It is shown that the 'S' shaped traces are produced by horizontally propagated acoustic-gravity waves under proper conditions. Relations between shapes and AGW's parameters are also given. These results are helpful in deducing some properties of AGWs from Doppler shift records.