磁暴环境下在线PPP服务系统性能评估

Location performance evaluation of online PPP service system for strong magnetic storm environment

针对当前面向强磁暴环境的在线精密单点定位(PPP)服务性能缺乏必要的评估分析,基于全球171个站点的全球卫星导航系统(GNSS)观测数据,系统性地评估了加拿大空间参考系统精密单点定位(CSRS-PPP)、自动精密定位服务(APPS)及内特-迪弗(Net_Diff)3种在线PPP服务系统,在2017-09-08强磁暴环境下的动态PPP定位性能。实验结果表明:在电离层平静环境下,3种在线PPP服务系统的动态PPP定位精度均可达厘米级。在强磁暴环境下,CSRS-PPP动态PPP定位精度为厘米级,且随着电离层异常强度的变化,定位性能变化不明显;APPS出现了数米的定位偏差,最大可超过10 m;Net_Diff动态PPP定位性能优于APPS,但在强磁暴环境下仍会出现数米的定位偏差。与中、低纬地区的GNSS跟踪站不同,强磁暴引起的电离层异常主要影响高纬GNSS测站的观测数据,从而影响在线PPP服务系统的定位性能。统计结果表明,CSRS-PPP、Net_Diff、APPS动态PPP的均方根(RMS)平均值分别为0.043、0.538、1.291 m。建议GNSS用户在强磁暴环境下首选CSRS-PPP在线服务。

Due to the inadequate analysis of current online precise point positioning(PPP) services in the strong magnetic storm environment, based on global navigation satellite system(GNSS) observation data from global 171 stations, this paper systematically evaluates the kinematic PPP performance using three online PPP service systems as Canadian spatial reference system-precise point positioning(CSRS-PPP), automatic precise positioning service(APPS), and Net_Diff during strong magnetic storm e nvironment on September 8, 2017. Ex perimental results show that the kinematic PPP results of all three online PPP service systems can reach centimeter level in the normally ionospheric environment. During strong geomagnetic storm, the kinematic PPP accuracy of CSRS-PPP still can reach centimeter level;and the positioning performance does not change significantly with the change of ionospheric anomaly intensity. That of APPS encounters several meters error and the maximum can reach 10 m. The kinematic PPP performance of Net_Diff is better than that of APPS. However, that of Net_Diff still encounters meter-level error during the strong storm. Different from GNSS tracking stations located in middle and low latitudes, the ionospheric anomalies caused by strong storms mainly affect GNSS observations of GNSS stations in high latitudes, thus affecting positioning performance of the online PPP service systems. Statistical results indicate that the average root mean square(RMS) values of kinematic PPP for the CSRS-PPP, Net_Diff, and APPS are 0.043, 0.538, and 1.291 m, respectively. Under strong storms, it is recommended that GNSS users prefer the CSRS-PPP online service.