大尺度电离层行扰的GPS观测

利用日本境内的高空间分辨率的双频GPS台站资料,观测研究了发生于2000年7月中旬太阳强活动期间的一次大尺度电离层行扰. 结果表明:在7月15日11:00UT-1:00UT期间观测区域的电离层中出现了大尺度电离层行扰. 在15:00UT之前,扰动周期为2h左右,在15:00UT以后,扰动周期为1h左右;总电子含量扰动幅度的变化范围约为1-2TECU;通过对15:00-17:00UT之间总电子含量扰动曲线同相位点的分析,发现这期间的电离层行扰的扰动速度约为600-700m/s,扰动波长在2200km左右,扰动传播的方向几乎沿着经线从高纬向低纬传播. 该行扰与此次强太阳活动有直接的关系,因其发生在7月15日的磁暴急始之前数小时,因此与磁暴本身没有因果关系,应与磁暴之前先期到达地球空间的高能质子流有关.

THE OBSERVATION OF LARGE SCALE TRAVELLING IONOSPHERIC DISTURBANCES BASED ON GPS NETWORK

A large scale travelling ionospheric disturbance （LSTID） during strong solar activity in the middle of July, 2000 is analyzed by means of the observation of high spatial resolution GPS network over Japan. It is found that a large scale travelling ionospheric disturbance occurred between 11:00UT and 18:00UT on July 15, 2000. Before 15:00UT the time period of LSTID is about 2h, then it becomes 1h or so. The amplitude of the disturbance is about 2 TECU. From the movement of the wave phase at different GPS station lined along same longitude, the phase velocity and wavelength of the travelling ionospheric disturbance between 15:00UT and 17:00UT is 600700 m/s and 2200 km. The wave propagates from higher latitude to lower latitude almost along the longitude line over observed region during this period. This TID has some relationship with the solar event occurred in the middle of July, 2000. Because the TID happened several hours before the sudden commencement of magnetic storm, the TID has not cause relation with the storm. The high flux of proton during the solar event should be responsible for this TID.