中低纬电离层F层峰高和厚度的变化特征分析

电离层F层参数对电离层空间天气研究与电波传播应用具有重要意义,以往工作主要针对电离层f_0F_2、TEC等参数.本文利用我国中纬地区的兰州、中低纬过渡区的昆明、低纬地区的海口三个观测站的电离层垂直探测数据,分析了电离层峰高h_mF_2、F层虚高h’F和定性表征的厚度h_mF_2—h’F的周日、季节、太阳活动变化特征.研究表明:(1)兰州h_mF_2在太阳活动高年和低年的数值接近,海口在太阳活动高年白天的h_mF_2比低年白天高20~30 km.(2)在海口和昆明,h_mF_2最大值多出现在中午时段,兰州站的最大值出现在夜间.(3)海口的h_mF_2在01-3LT期间出现很强的"午夜衰落"现象,此后迅速增大.(4)利用h_mF_2-h'F来表征电离层的厚度时,其季节和周日变化特征与常用的B_0存在相似之处,但未出现清晨与午后凹陷等现象.这些结果对于提高我国电离层变化特性的认识和模式化研究水平具有重要的科学意义.

Analyzing peak height and thickness variation characteristics of ionospheric F-layer at middle and low latitudes

The parameters of the ionosphere F-layer have important influence on space weather research and radiowave propagation application. Previous work mainly focused on the parameters of f₀F₂ and TEC etc. The statistical analysis of diurnal, seasonal and solar activity variation about the ionosphere F-layer peak height h_mF₂, virtual height h'F, and h_mF₂-h'F which is used to qualitatively characterize the thickness is presented in this paper by using ionosonde data of Lanzhou, Kunming and Haikou at middle to low latitudes in China. The main results showed that: (1) h_mF₂ at solar max is close to the results at solar min in Lanzhou. The h_mF₂ at solar max in Haikou was bigger than that in solar min by 20~30 km. (2) the biggest h_mF₂ occurs at noon in Haikou and Kunming. But it appears at night in Lanzhou. (3) h_mF₂ presented the strong 'midnight decline’ phenomena during 01-03 LT in Haikou, since then increased rapidly. (4) the seasonal and diurnal variation characteristics when using the h_mF₂-h'F to characterize the ionosphere thickness is similar with that of commonly used parameter B₀. But there is not sunken phenomenon in the early morning and afternoon. These results have important scientific significance for us to enhance the cognition for variation characteristics and modeling research level of ionosphere in China.