SLR不同地心运动确定方法研究及其特征分析

处理了Lageos-1,Lageos-2,Etalon-1和Etalon-2共4颗卫星在1993―2017年的全球卫星激光测距(satellite laser raging,SLR)观测数据,并对国际激光测距服务(International Laser Ranging Service,ILRS)各分析中心(analysis centers,ACs)的周解进行了技术内综合,分别通过几何法(参考SLRF2008和SLRF2014)和直接法(针对Lageos-1和Lageos-2)确定了SLR地心运动序列;利用傅里叶变换和最小二乘法分析了地心运动的长期变化、周年变化和半年变化,并与CSR(the center for space research)提供的动力学法结果进行了比较和分析。结果表明:地心运动的长期项比周期项小1个量级;与SLRF2008几何法相比,用SLRF2014几何法得到的地心运动长期项明显较小,特别是在Z方向;使用直接法分别针对Lageos-1和Lageos-2卫星激光测距数据解算的地心运动半年项有较好的一致性,但周年项相位相差较大,且在Z方向与几何法及CSR提供的动力学法结果差异也很大,这可能与该方法解算的地心运动与测站偏心改正强相关有关,也可能与单颗星解算地心运动几何结构不够好有关;使用几何法得到的地心运动与CSR动力学结果非常接近,证明利用上海天文台和ILRS ACs周解进行技术内综合来确定地心运动的方法是可行的。

Method Research and Feature Analysis on the Geocenter Motion Derived from SLR

The global SLR observation data of Lageos-1,Lageos-2,Etalon-1 and Etalon-2 from 1993 to 2017 were processed and combined with the weekly solutions of the ILRS analysis centers(AC).Then with the geometry and direct methods we get the time series of geocenter motion.The series are analyzed by Fourier transform and least squares methods to obtain the secular,annual and semi-annual variations of geocentric motion,and then compared with the results derived from dynamic method provided by CSR.The results show that the secular variations are one order of magnitude smaller than periodic variations.Compared with SLRF2008,the secular variations in geocenter motion are greatly reduced when using the origin defined by SLRF2014,especially in the Z direction.The geocenter motion calculated by the direct method from Lageos-1 and Lageos-2 satellites respectively show a good consistency on semi-annual term,but the phase of annual term is quite different.Additionally,the results of the direct method have a big offset with the result derived from the geometry method and dynamic method provided by CSR in the Z direction,which may due to the strong correlation between the geocenter motion calculated by this method and the eccentricity corrections,or may be related to the poor geometry by using one single satellite;the geocenter motion obtained by the geometric method has a good consistency with that of CSR,demonstrating the feasibility of combining SHAO and ILRS ACs’weekly solutions to determine the geocenter motion.