利用全球IGS站GPS数据确定地球自转参数

Earth Rotation Parameters Determination Based on Daily GPS Data of Global IGS Stations

地球自转参数是天球坐标系与地固坐标系相互转换不可缺少的物理参数，也是卫星精密定轨、高精度深空导航与定位必不可少的重要基础数据。本文基于附有约束条件的最小二乘估计，给出了利用全球IGS站GPS数据确定极移、极移变率和日长变化等地球自转参数的基本原理和算法。利用2009年8月18日至27日共10天的全球110个IGS站数据获得了GPS卫星轨道和地球自转参数的估计结果。计算表明：由全球IGS数据可获得优于4cm的GPS卫星3D轨道精度和2．2cm的1D轨道精度；极移X、Y分量的精度分别约0．15mas和0．1mas，极移精度优于0．2mas；极移变率X、Y分量的精度分别约0．18mas／d和0．16mas／d，极移变率精度优于0．27mas／d；日长变化精度约0．02ms／d，相比较而言，日长变化解算的稳定性要低于极移参数。

Earth rotation parameters （ ERPs ） are necessary parameters to achieve mutual transformation of the celestial ref- erence frame and earth - fix reference frame. They are very important for satellite precise orbit determination （ POD } , high - pre- cision space navigation and positioning. In this paper, the determination of ERPs including polar motion （ PM ） , polar motion rate （PMR} and change in length of day （LOD） are presented using daily GPS data of global IGS stations based on the least square （LS） estimation with constraint condition. GPS data of 110 global IGS stations from Aug 18 to Aug 27, 2009 are used to estimate the ERPs as well as GPS orbits. The results show that the accuracy of GPS POD is better than 4 cm in three - dimension and 2. 2 cm in one - dimension. The mean RMS of x and y component errors of PM are about 0.15 mas and 0.1 mas respectively. The total RMS of PM errors is less than 0.2 mas. The mean RMS x and y component errors of PM rate are about 0.18 mas/d and 0. 16 mas/d. The total RMS of PM rate errors is less than 0.27 mas/d. As for LOD, the mean RMS is about 0.02 ms/d. All these conclusions prove the validation of the ERP determination proposed by this paper.