电离层E/F层闪烁对GPS TEC变化率的影响

Impact of E/F layer ionospheric scintillation on GPS TEC changing rate

电离层闪烁是一种能够降低导航性能的自然现象,主要发生在极区和低纬度地区电离层的不同高度层中,包括E层和F层。为研究电离层E/F层闪烁对地面站估算的GPS总电子含量(TEC)变化率指数(ROTI)的不同影响,借助COSMIC观测系统以及高速率GPS双频大地测量数据展开详细分析,同时也探讨GISM模型对其的预测能力。结果表明:电离层E层发生强闪烁(S4> 0.6),GPS ROTI未发生较大变化(ROTI≈0.02 TECU/min);而F层发生强闪烁时,ROTI则出现明显变化(ROTI≥2 TECU/min);GISM模型能够预测香港区域电离层夜间发生的强闪烁(预测值S4≥0.6),但对于白天发生的闪烁模型预测S4结果均为0,此外,GISM模型预测结果中对电离层E/F层闪烁并无区分。

As a natural phenomenon which is possible to reduce navigation performance, ionospheric scintillation mainly occurs in different heights of ionosphere layers at polar area and low latitudes including E/F layers. In order to investigate the effects of E/F layer ionospheric scintillation on ROTI estimated by GPS ground stations, COSMIC and high rate GPS dual-frequency geodetic surveying data are used to conduct detailed analyses. Meanwhile, the predicting ability of GISM is also investigated. Result shows that GPS ROTI is small （ROTI ≈0.02TECU/min） when E-layer strong scintillation occurs （S4〉0.6）, however, ROTI becomes very large （ROTI≥2 TECU/min） when F-layer strong scintillation occurs. Take Hong Kong district as instance, GISM is capable to predict ionospheric scintillation occurring at night （S4 predicted value ≥ 0.6 ） while predicted S4 value of daytime scintillation is totally zero. Besides, there is no difference between ionospheric scintillation of E/F layers according to CISM predicted results.