拉萨地区电离层长期变化特性研究

电离层环境变化对电子信息系统有重要影响，因此电离层变化特性研究具有重要意义.文中根据拉萨电波环境观测站30余年数据，研究了拉萨地区电离层F层临界频率f_oF₂、F层底高h'F、Es层临界频率f_oEs的日变化、季节变化和长期变化情况，得到一些有意义结论:电离层f_oF₂全年均值介于3~11 MHz，日变化显著，季节变化明显，随太阳活动变化幅度较大；电离层h'F全年均值介于200~420 km，日变化显著，随季节变化不明显，与太阳周期变化呈正相关关系；电离层f_oEs全年均值介于1~7 MHz，日变化显著，季节变化显著（夏季明显高于其他季节），太阳周期变化不明显.研究电离层环境的长期变化特性，获取电离层参数长期变化规律，对通信导航、航天器等装备的设计和运行维护具有重要意义.

Long-term ionospheric characteristics over Lhasa

It is important to study ionospheric characteristic for researching electron equipments impacted by ionosphere. There are important effects on the electron equipments for the variations of ionosphere, such as it can induce shortwave communications quality decline indeed interrupted, navigation signal scintilla and error increase, space probe orbit change, charge up and proton event etc. Based on Lhasa's data of ionospheric vertical sounders more than 30 years, we researched the daily variations, seasonal changes and long-term trends of the ionosphere of Lhasa, and get some meaningful conclusions. The annual means of ionospheric f_oF₂ are between 3-11 MHz, the daily changes of ionospheric f_oF₂ are significant, and the seasonal changes are also obvious, the f_oF₂ varies greatly with solar activities. The annual means of ionospheric h'F are between 200-420 km, the daily changes of ionospheric h'F are significant, and the seasonal changes are unconspicuous, there are positive correlation between h'F and solar cycle changes. The annual means of ionospheric f_oEs are between 1-7 MHz, the daily changes and the seasonal changes of ionospheric f_oEs are significant as well, yet the solar cycle changes are not noticeable. Studying the long-term variation of the ionosphere and obtaining the long-term change rule is important to the design and maintenance of communication navigation, spacecraft equipments.