BDS GEO卫星的电离层VTEC反演性能评估

Evaluation of ionospheric VTEC inversion performance for BDS GEO satellites

北斗卫星导航系统(BDS)的地球同步轨道(GEO)卫星可以对固定穿刺点总电子含量(TEC)进行连续观测,可为电离层模型精化提供约束,但BDS GEO卫星探测范围包含了20000 km以上的稀薄等离子体,为了进一步研究其对TEC反演造成的影响,提出一种性能评估方法:利用BDS GEO卫星双频观测数据提取电离层穿刺点处的垂向电子总含量(VTEC);然后分析穿刺点处VTEC变化特性,并与全球电离层图、相邻中圆轨道(MEO)卫星反演VTEC比较;最后以经验电子模型为参考,评估2种卫星探测的等离子体层总电子含量。结果表明:研究区域内GEO-VTEC与全球电离层图有较好的一致性;在不同的地磁条件下,GEO-VTEC与MEO-VTEC偏差的均方根值接近,最大不超过2.46个总电子含量单位;GEO与MEO卫星探测的等离子体层TEC值接近,20000 km以上的等离子体对于TEC的影响可以忽略。说明GEO-VTEC与常用电离层产品以及MEO-VTEC的性能一致。

Geostationary Earth orbit(GEO)satellites of BeiDou navigation satellite system(BDS)can continuously observe the fixed puncture point's total electron content(TEC)and provide reliable constraints for refining the ionospheric model,however,the detection range of BDS GEO satellites contains more than 20000 km of dilute plasma,thus in order to further study the impact of BDS GEO satellites on TEC inversion,the paper proposed a perfromance evaluation method:the vertical total electron content(VTEC)at the ionospheric puncture point was extracted by using dual-frequency observation data from BDS GEO satellites;and then the variation characteristics of VTEC at the puncture point were analyzed and compared with the reversed VTEC of global ionospheric map(GIM)and the adjacent medium Earth orbit(MEO)satellites;finally,an empirical electron model was used as a reference to evaluate the TEC of the plasma layer detected by the two kinds of satellites.Results showed that the GEO-VTEC in the study area could be in good agreement with the GIM;and under different geomagnetic conditions,the root mean square of the deviation between GEO-VTEC and MEO-VTEC would be close,with a maximum difference of no more than 2.46 total electron content units;moreover,the TEC values of the plasma layer detected by GEO and MEO satellites would be similar,and the influence of plasma above 20000 km on TEC could be ignored;in general,it could be demonstrated that the performance of GEO-VTEC could be consistent with common ionospheric products and MEO-VTEC.