摘要
电离层掩星观测中,当低轨卫星(LEO)轨道高度较低时,轨道以上的电离层电子总含量(TEC)对掩星反演的影响不能忽略.目前,一般采用指数函数等外推方法来处理该问题,对反演结果可能引起较大误差.为提高电离层掩星反演精度,本文研究利用LEO处于非掩星一侧GPS观测数据的改正TEC新反演方法.用三维射线追踪程序计算出电离层掩星观测模拟数据,分别应用改正TEC方法和外推方法进行反演,将反演结果与所用模式值进行比较.结果表明:对于轨道高度约800km的GPS MET掩星模拟数据,外推方法和改正TEC方法反演结果都与模式值基本一致;对于轨道高度约400km的CHAMP掩星模拟数据,外推方法误差较大,改正TEC方法反演结果与模式值相符得较好.将改正TEC方法应用于GPS MET实测数据的反演,取得了合理的结果.这些说明,改正TEC算法是一种有效的电离层掩星反演方法,尤其是对于轨道较低的LEO的电离层掩星观测反演特别有用.
When the low-Earth orbit （LEO） satellite is low, the contribution of the Total Electron Contents （TEC）above the satellite is not neglectable for inversion of GPS-LEO ionospheric occultation. The exponential extrapolate method which is widely used now may induce a big error, especially when LEO＇ s orbit is lower. We propose an inversion algorithm, calibrated TEC method, to estimate the TEC above LEO using the data from the non-occultation portion of the satellite track. We use the three-dimensional ray-tracing program to simulate the ionospheric occultation. Then we inverse the simulation data by the calibrated TEC method and exponential extrapolate method, and the results are compared with the model values. The results show that, for GPSIMET, the inversion profiles of the extrapolate method and the calibrated TEC method agree with the given model ionosphere, and the calibrated TEC method is better than the extrapolate method at higher altitude. ForCHAMP, the errors of extrapolate method are large, and inversion profiles of the calibrated TEC method are consistent with the model values. Then, the calibrated TEC method is applied to the processing of actual GPS/ MET ionospheric occultation data, and the inversion profiles are reasonable. These prove that the calibrated TEC method is a good algorithm for inversion of ionospheric GPS occultation, especially when the LEO＇ s orbit is low.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第2期328-334,共7页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(40204011)资助.
