章动改正项的周期分析及拟合研究

Period Analysis and Fitting of Nutation Correction Term

章动作为地球定向参数(earth orientation parameter,EOP)的重要组成部分,是进行地心天球参考系(geocentric celestial reference system,GCRS)和国际地球参考系(inter⁃national terrestrial reference system,ITRS)转换时的必要参数。本文利用国际地球自转服务(International Earth Rota⁃tion and Reference Systems Service,IERS)提供的章动改正项进行频谱分析及周期项的提取,实验结果表明,黄经章动以及黄赤交角章动改正值,在趋势项和周期项区别较小,故在一般的研究中,可使用IERS网站发布发章动改正值来代替真实的章动。频谱分析实验结果表明,其章动数据更加能体现数据的高频特性。采用最小二乘外推模型和多项式曲线拟合方法对之前提取到的黄经章动改正项进行拟合,结果表明,最小二乘外推模型方法基本可以实现章动改正值的预报,虽然精度有限,但依然可以适用一些精度要求不高的研究。本文研究结果可为地球定向参数的预报研究提供参考。

Nutation is an integral part of the Earth Orientation Parameter(EOP).It is a necessary parameter for converting the geocentric celestial reference system(GCRS)and the in⁃ternational terrestrial reference system(ITRS).In this study,we use the corrected chapter motion terms provided by the International Earth Rotation and Reference Systems Ser⁃vice(IERS)for spectral analysis and extraction of the period terms.The nutation values of the longitude and the Angle of the ecliptic are not very different from the nutation values in terms of trend and period terms.For general studies,we can use the website of the IERS to replace the actual nutation val⁃ues to show some characteristics of nutation.The experimen⁃tal results of spectrum analysis show that compared with EOP 08 C04,the data of EOP 14 C04 can better reflect the highfrequency characteristics of the data.By using the least square extrapolation model and polynomial curve fitting method to ex⁃tract the longitude appropriate correction nutation,the experi⁃mental results show that the least squares model extrapolation method essential can realize the dynamic correction value of nutation forecasts;although the accuracy is limited,it still suitable for some application requirements with low precision.The results of this study can be used as a reference for research on the forecasting of steering parameters.