重庆地区电离层Es的遮蔽特性研究

目的 研究获得重庆地区电离层Es的遮蔽特性，以及强Es对短波链路可用频率的影响，为相关无线电系统设计和使用提供依据。方法 对2008—2018年期间重庆站电离层观测数据进行统计分析，得到Es临界频率和遮蔽频率的变化规律。引入遮蔽因子，分析Es遮蔽因子随地方时、季节的变化特征。利用新乡–昆明站短波链路试验数据，对强Es期间的链路可用频率变化情况进行验证。结果 重庆地区Es主要发生在夏季白天，峰值强度出现在6月份的上午，临界频率约为8MHz。遮蔽因子的峰值出现在7月份，最大值约为0.8，且在日出前遮蔽效果较其他时刻显著。全遮蔽Es可发生在各地方时，平均发生率约为10%，峰值位于上午，峰值发生率约为21%。发生强Es遮蔽时，能够到达电离层F层并被反射的短波链路最低可用频率增加，特别是在白天。通过Es散射的链路最高可用频率显著增加，平均增加约10 MHz。结论 重庆地区电离层Es的遮蔽程度主要随地方时和季节变化，随太阳活动的变化较小。Es的遮蔽程度在夏季的上午达到最强，在春秋季较弱。强Es期间，依靠电离层F层反射传播的短波链路最低可用频率增加，导致可用频段变窄，同时利用电离层Es散射传播的链路...

Obscure Properties of Ionospheric Sporadic-E over Chongqing

The work aims to obtain the obscure properties of ionospheric sporadic-E over Chongqing, and its effects on the usable frequency of high frequency links, and provide a basis for related design and operation process of radio systems. After a statistical study on ionosonding data of Chongqing station from 2008-2018, the variabilities of the critical and obscure frequencies of sporadic-E were obtained. The obscure factor was adopted to analyze the change of sporadic-E obscure factor with local time and season. Experimental data from a short-wave radio propagation link, Xinxiang-Kunming, were used to validate the change of usable frequency of the link during strong sporadic-E. The result showed that the sporadic-E over Chongqing mainly occured in daytime of summer. The peak strength of foes appeared in the morning of June, with an average critical frequency of about 8 MHz. The obscure factor reached its peak value in July with a magnitude of about 0.8, which was more significant before sunrise. The entire obscurity could happen at any local time, but occured more often before noon. The average occurrence rate of entire obscurity is about 10%, with a peak value of 21%. When strong sporadic-E occured, the lowest usable frequency of the short-wave link that propagated into the ionospheric F region and was reflected to the ground was raised especially in the daytime. On the other hand, the maximum usable frequency refracted by Es also increased, with the maximum magnitude of about 10 MHz. It is concluded that the obscure property of sporadic-E over Chongqing changes much with local time and season, but little with solar activity. The obscure magnitude reaches its peak value in the morning in summer, but it is much weak in equinoxes. When strong sporadic-E occurs, the lowest usable frequency of short-wave links relying on the ionospheric F region is raised, which leads to a reduction of usable band. Meanwhile, the highest usable frequency of links transmitted by virtue of the sporadic-E scattering in ionosphere also increases to a certain extent.