利用数据同化技术实现区域电离层TEC重构

Regional Ionospheric TEC Reconstruction by Data Assimilation Technique

电离层参量的提取是开展电离层研究的基础,而数据同化技术则是获取电离层参量的一种重要手段。以NeQuick模型的输出作为背景场,Kalman滤波作为同化算法,利用数据同化技术实现区域电离层TEC重构,结果表明,数据同化方法重构的倾斜总电子含量(TEC)和垂直TEC与实测值较为一致。相比NeQuick模型及全球电离层地图(GIM)数据,数据同化方法重构得到的TEC的平均误差和标准差均有明显的降低,实测数据验证了数据同化技术在区域TEC重构中的精度和可靠性。

Accurate determination of the state of ionosphere has become a key point as radio-wave information systems become more spatially dependent.Data assimilation technique is an important method to obtain ionospheric parameters that is useful in ionospheric study.To provide specification of the ionosphere total electron content（TEC）for current conditions,a new ionospheric TEC reconstruction method is developed in this paper by utilizing data assimilation technique.With the output of NeQuick model as background field and Kalman filter as assimilation algorithm,regional three dimensional ionospheric electron density reconstruction can be implemented by data assimilation of 39 GPS observations from continuously operating reference stations（CORS）of NOAA（National Oceanic and Atmospheric Administration）,while TEC map can be obtained by vertical integral of electron density al.For reducing the reduction in the computational requirements,the regional TEC maps are generated accordingly with the spatial and temporal resolution being 2.5°×5°and 1hour respectively.Data assimilation results have been validated through the comparison with 10 independent GPS observations,the NeQuick model values and the global ionosphere maps（GIM）from Center for Orbit Determination of Europe（CODE）over 31 days in December,2014.Results show that data assimilation derived TEC maps are more effective in reducing the mean error and standard error of TEC than NeQuick model and GIM data.These results demonstrate the potential of data assimilation technique in providing accurate regional or even global specification of the ionosphere.