使用COSMIC掩星提供的NmF2数据,利用傅里叶分析方法,研究全球F2层峰值电子密度的周年和半年分布特征,分析2010年LT12:00 14:00 NmF2周年和半年变化幅度及2008-2011年年平均值变化.结果显示,电离层NmF2周年和半年变化幅度在中高纬地区相对较大;在赤道和低纬地区相对较小,且NmF2以半年变化为主.太阳活动增强期间,NmF2年平均值增大.
With the Fourier analysis method, the global NmF2 annual and semiannual variations are investigated by using COSMIC occultation data. We analyze annual and semiannual varia- tions of NmF2 and its annual average value variations during the period of 2008--2011. Re- search shows that global NmF2 annual and semiannual variations are strong in the middle and high latitudes, and weak in the low latitudes and equatorial region. In the low latitudes and equatorial region, NmF2 is mainly dominated by semiannual variation.