GPS卫星轨道及钟差对GRACE卫星定轨精度影响

Impact of GPS Satellite Orbit and Clock on GRACE Satellite Orbit Determination

针对GPS卫星精密轨道和钟差插值对GRACE卫星定轨精度影响进行了分析,分别使用IGS(International GNSS Service)30 s间隔钟差、CODE(the Center for Orbit Determination in Europe)30和5 s间隔钟差以及15 min精密星历进行GRACE卫星定轨实验。结果表明:GPS轨道插值精度可以达到cm级,将15 min GPS轨道插值为30 s间隔利用9阶拉格朗日插值定轨结果精度最高,继续增加阶数定轨精度不会增加;利用CODE钟差计算GRACE非差运动学轨道,码伪距结果精度较IGS产品提高6%,载波相位运动学定轨结果和约化动力学定轨结果精度都提高10%左右;5 s间隔卫星钟数据对定轨结果改进并不明显。采用CODE间隔为30 s钟差进行GRACE运动学定轨的计算精度能满足cm级轨道的应用需求。

The influence of GPS satellite precise orbit and clock error interpolation on the accuracy of GRACE satellite orbit determination is analyzed.The experiments of GRACE kinematics orbit determination are carried out respectively using the 30 s sample interval GPS clock from IGS(International GNSS Service),30 s or 5 s sample interval GPS clock from CODE(the Center for Orbit Determination in Europe)and 15 min interval precise ephemeris.The results show that the accuracy of GPS orbit interpolation can reach centimeter level,and when the 15 min interval GPS orbit is interpolated to 30 s,using 9 order Lagrangian interpolation to determine the orbit has the highest accuracy,and if continue to increase the order,the accuracy will not increase.The GRACE satellite kinematic orbit calculated by CODE clock comparing with calculated by IGS product,the accuracy of code pseudorange orbit is improved by 6%,and the accuracy of carrier phase kinematics orbit and reduced-dynamic orbit results is improved by about 10%.The improvement of the result is not obvious by using the 5 s sample interval satellite clock data.The GRACE kinematics orbit determination accuracy with 30 s sample interval from CODE meets application requirements.