一种联合地基GNSS和测高仪数据的电离层层析成像新算法

A new hybrid ionospheric tomography algorithm by combining ground-based GNSS and ionosonde data

电离层层析成像(computerized ionospheric tomography,CIT)技术是获取区域大范围电离层三维结构非常重要的手段之一.针对单独使用地基GNSS进行三维CIT的不足,提出了一种联合地基GNSS和测高仪数据的三维CIT方法,其综合了测高仪探测电离层垂直分辨率较高和地基GNSS水平分辨率较高的优点,以测高仪数据驱动更新IRI模型,将更新后的IRI模型作为背景电离层模型,再利用改进的代数重建迭代(algebraic reconstruction technique,ART)算法结合地基GNSS TEC数据进行CIT;基于IGS、中国陆态网地基GNSS台站及全球电离层无线电观测网(global ionospheric radio observatory,GIRO)测高仪数据实现了中国及周边区域三维CIT,分别采用Madrigal TEC数据和中国区域独立的测高仪数据对CIT获取的TEC和电子密度进行评估.TEC精度评估结果表明,CIT算法的TEC平均误差和标准差相比IRI模型及CODE GIM数据均有明显降低;电子密度评估结果表明,单纯依赖地基GNSS进行CIT可以提升foF2的精度但无法有效提升hF的精度,而联合测高仪数据后,电离层foF2和hF的重构精度均有明显提升,其中hF的平均误差和标准差从20.6 km和16.5km下降为14.8 km和11.7 km,说明测高仪数据对CIT垂直分辨率的提升作用明显.

Computerized ionospheric tomography(CIT)is one of the most important means to obtain the threedimensional structure of the ionosphere in a wide range of regions.In view of the deficiency of using ground-based GNSS for ionospheric 3D tomography alone,a new hybrid ionospheric tomography algorithm by combining groundbased GNSS and ionosonde data is proposed.The algorithm combines the advantages of high vertical resolution of ionosphere detected by ionosonde and high horizontal resolution of ground-based GNSS CIT.The updated IRI model by ionosonde data is used as the background ionospheric model,and then the improved ART algorithm combined with ground-based GNSS TEC is used for tomography.Based on the data of IGS,the crustal movement observation network of China(CMONOC)and GIRO ionosonde,the three-dimensional ionospheric tomography of China and its surrounding areas is realized.Madrigal TEC data and independent ionosonde data in China are used to evaluate the TEC and electron density obtained by tomography.The results of TEC accuracy evaluation show that the TEC average error and standard deviation of CIT algorithm are significantly lower than those of IRI model and CODE GIM data.The electron density evaluation results show that only relying on the ground-based GNSS for CIT can improve the accuracy of foF2 but can not effectively improve the accuracy of hF;after combining the ionosonde data,the reconstruction accuracy of ionospheric foF2 and hFis significantly improved,in which the average error and standard deviation of hFdecreases from 20.6 km and 16.5 km to 14.8 km and 11.7 km,and the ionosonde data play a significant role in improving the vertical resolution of CIT.