海南地区扩展F统计特性及行星波扰动观测

Statistical Characteristics of Spread-F and Observations of Planetary Wave Disturbances in Hainan

为研究中国低纬地区扩展F(SF)的发生时间和季节特性以及行星波扰动对其影响,利用2013年海南三亚综合观测站DPS-4D数字测高仪观测到的电离层频高图数据,统计分析了扩展F的开始和持续时间及其季节变化;提取了电离层虚高,从虚高的逐日变化中获取了F层上抬时间和行星波扰动特征,并对上抬期间电离层F层最小虚高(h'F)、临界频率(fo F2)等参数进行了小波分析.结果表明:海南地区扩展F类型主要为RSF,其季节性最大值(51%)出现在分点季,RSF在日落后和午夜后均有发生,而FSF主要在夏季午夜后出现;海南地区电离层虚高在日落后反转增强(PRE)期间有明显上抬现象,电离层特征参数中存在周期为准2d、5d以及10d的行星波扰动,它通过调制电离层F区发电机电场的方式激励扩展F的发生和发展.

In this paper, the ionograms recorded by the DPS-4D digisonde at Sanya ionospheric observatory station in 2013 are used to study the onsets, durations and seasonal variations of the spread-F （SF）.The uplift time of F-region and the planetary wave disturbances are obtained from the daily virtual height variations extracted from the ionograms.The minimum virtual height （h＆#39;F） and the critical frequency of F layer （foF2）, etc.are analyzed with wavelets transform during uplift.The results show： The RSF is the main type with a seasonal maximum value about 51% in equinox in Hainan.RSF occur from post-sunset to post-midnight, while FSF mainly appear at post-midnight during summer months.There are obvious elevations of virtual height during pre-reversal enhancement （PRE）.There are planetary wave disturbances with quasi 2-day, 5-day and 10-day periods of the ionospheric characteristic parameters and they drive the initiation and the development of SF by modulating dynamo electrical field in the ionospheric F-region.