利用GPS三频数据计算电离层垂直总电子含量变化率

Calculation of rate of change of ionospheric vertical total electron content using triple-frequency GPS data

研究了通过采样间隔为1 s的GPS三频载波相位观测数据计算1 Hz电离层垂直总电子含量变化率(RVTEC)的方法,推导了直接采用双频载波相位观测量计算RVTEC的公式,对一般空间环境与电离层活动剧烈两种条件下L1L2、L1L5、L2L5三种载波相位组合计算的RVTEC进行了一致性分析,给出了通过三频载波相位观测数据计算电离层RVTEC的修正方法,比较了X射线太阳耀斑期间RVTEC与由传统方法计算的总电子含量变化率(ROT)响应,在双星串飞编队测高模式下对计算方法进行了应用.结果表明,L1L2、L1L5两种组合之间的一致性较好,由L1L2、L1L5组合计算的RVTEC的中误差约为0.004 TECu/s,RVTEC较ROT更能体现TEC变化的细节,在双星串飞编队测高模式下海面高梯度的计算中,电离层延迟之差可以忽略.

The method of calculating the change rate of ionospheric vertical total electron content （RVTEC） at 1Hz using triple-frequency GPS carrier-phase observations of ls interval was studied. The formula for calculating RVTEC using dual-frequency carrier-phase observations directly was deduced. The consistency of RVTEC calculated from the combination of L1L2, L1L5 and L2L5 was analyzed in common space environment as well as disturbed ionosphere. A modified method of calculating RVTEC using triple-frequency carrier-phase observations was given, and the response of RVTEC and the change rate of total electron content （ROT） calculated with conventional method during X-ray solar flare were compared. The modified method was applied in dual-satellite formation altimetry mode, and the results showed that the combination of L1L2 and LIL5 had a good consistency, with a mean square error of RVTEC of 0. 004 TECu/s. Besides, RVTEC provided more details of TEC change compared with that of ROT, and the difference of ionospheric delay could be omitted when calculating the sea surface height gradient in dual- satellite formation altimetry mode.