一种基于分步线性最优估计的全球中低纬区域电离层f_(o)F_(2)重构方法

A method of ionospheric f_(o)F_(2)reconstruction in low and middle latitudes of the world based on stepwise linear optimal estimation

电离层F2层临界频率f_(o)F_(2)是短波通信、探测和电子对抗等领域最为重要的应用参数之一.针对全球范围内电离层测高仪分布较为稀疏的特点,基于全球电离层无线电观测站(Global Ionospheric Radio Observatory,GIRO)的测高仪实测数据,采用分步线性最优估计方法对电离层CCIR/URSI系数进行调整,实现了全球中低纬区域电离层f_(o)F_(2)的重构.对2010—2016年的电离层f_(o)F_(2)重构结果进行分析,结果表明:在纬度变化上,中纬区域重构误差要低于低纬区域;在年变化上,重构的绝对误差和均方根误差有随太阳活动强度增强而增大的趋势,重构的相对误差无明显年变化;在季节变化上,夏季重构误差最小,其他三个季节相差不大;在地方时变化上,白天的重构误差低于夜间.总体而言,相比于国际参考电离层(international reference ionosphere,IRI)模型,电离层f_(o)F_(2)重构的绝对误差和均方根误差分别下降了约38%和34%,验证了本文方法的有效性和可靠性.

The ionospheric F2 critical frequency f_(o)F_(2)is one of the most important application parameters in the fields of short-wave communication,detection and electronic countermeasures.Based on the ionosonde data from the Global Ionospheric Radio Observatory(GIRO),the ionospheric CCIR/URSI coefficients are adjusted by the stepwise linear optimal estimation method to reconstruct the ionospheric f_(o)F_(2)in the middle and low latitudes of the world.The results of ionospheric f_(o)F_(2)reconstruction from 2010 to 2016 show that the reconstruction error in mid-latitude region is lower than that in low-latitude region in latitude variation.In the annual change,the absolute error and root mean square error of reconstruction have a tendency to increase with the increase of solar activity intensity,and the relative error of reconstruction has no obvious annual change.In the seasonal variation,the reconstruction error in summer is the smallest,with little difference in the other three seasons.Compared with the IRI model,the absolute and root mean square errors of ionospheric f_(o)F_(2)reconstruction are reduced by 38%and 34%respectively,which proves the validity and reliability of the proposed method.