利用北斗观测数据实时监测中国区域电离层变化

北斗卫星导航信号采用三个频点工作，可以利用伪距双频组差方法解算电离层电子含量，为实时监视中国区域电离层变化提供新的技术手段.中国中低纬度处于电离层赤道异常变化区，在北纬20°±5°区域时常发生较大梯度的电离层变化.利用北斗实时多频伪距和相位观测数据，采用相位平滑伪距方法计算电离层穿刺点电子含量，分析通过北斗系统GEO卫星监测的电离层周日变化特性；采用多面函数方法拟合中国区域1°×1°分辨率的电离层延迟量，每5min绘制一幅中国区域电离层图，观测区域所有电离层穿刺点拟合残差RMS为2.778TECU；分析北斗系统实时监测中国区域电离层异常情况，当发生电离层异常变化时，相邻两天的VTEC（Vertical Total Electronic Content）峰值相差约60TECU. 

Real-time Monitoring Regional Ionospheric Variety of China with BDS Observations

BDS provides uninterrupted PNT service for Asia-Pacific area since 27 December 2012, when China released an official version of the complete BDS Interface Control Document (ICD) for open service Signal-In-Space (SIS). Because BDS signals working at three frequencies, ionospheric delay can be calculated with pseudo-range dual-frequency combination technique and a new technique to monitor ionospheric variety over China is established. Lower-middle latitude area of China is in the ionospheric equator anomalies region and large grads ionospheric varieties often occur within the area of north latitude 20°±5°. Daily variety characteristic of ionospheric delay measured with BDS GEO satellites is analyzed by using BDS real-time pseudo-range observation and adopting carrier phase smoothed pseudo-range. China region ionospheric map is painted in 1°×1° scale with polyhedral fitting every 5 minutes and the average fitting error RMS of all Ionospheric Punch Point (IPPs) is 2.778TECU. The ionospheric anomalies around China monitored with BDS observation shows that the VTEC peak difference between adjacent two days can be 60TECU when large scale ionospheric anomaly occurs.