Recommendations for construction of a nonlinear international Terrestrial Reference Frame  

作　　者：ZHU WenYao SONG ShuLi HE LiNa 

机构地区：[1]Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China [2]Department of Surveying and Geo-informatics, Tongji University, Shanghai 200092, China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2011年第1期164-171,共8页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No.10603011);the National High Technology Research and Development Program (Grant No.2009AA12Z307);the Science and Technology Commission of Shanghai Municipality (Grant Nos.05QMX1462 and 08ZR1422400);the Youth Foundation of Knowledge Innovation Project of the Chinese Academy of Sciences,Shanghai Astronomical Observatory (Grant No.5120090304)

摘　　要：The problems of ITRF2008,the latest International Terrestrial Reference Frame,are pointed out and analyzed as follows:(1) ITRF is not a mm-level Terrestrial Reference Frame;(2) the origin of ITRF is neither the Earth's center of mass (CM) nor the center of figure (CF);(3) the scale of ITRF is not a uniform system in the sense of the gravitational theory of relativity.These problems result from the linear hypothesis used in the establishment and maintenance of ITRF,which includes the linear hypothesis of the coordinates definition of the ITRF reference stations,and the seven coordinate transformation parameters (three translation parameters,three rotation parameters,and one scale parameter) when the ITRF combine solution is constructed.The linear hypothesis of the ITRF construction leads to the current terrestrial reference frame only at the cm-level,which cannot satisfy the requirements of monitoring mm-level crust movements as well as the global environment.This article points out that the construction of a mm-level Terrestrial Reference Frame is actually a leap from linear to nonlinear.Therefore,according to the main characteristics of nonlinear changes of the crust's deformation,the geocenter motion and the overall height fluctuation of the Earth,the new ITRF station coordinates definition and the new observation equations of combined solutions are constructed for the realization of a mm-level nonlinear ITRF,which can solve the problems of the current ITRF.The problems of ITRF2008,the latest International Terrestrial Reference Frame,are pointed out and analyzed as follows：（1） ITRF is not a mm-level Terrestrial Reference Frame;（2） the origin of ITRF is neither the Earth＇s center of mass （CM） nor the center of figure （CF）;（3） the scale of ITRF is not a uniform system in the sense of the gravitational theory of relativity.These problems result from the linear hypothesis used in the establishment and maintenance of ITRF,which includes the linear hypothesis of the coordinates definition of the ITRF reference stations,and the seven coordinate transformation parameters （three translation parameters,three rotation parameters,and one scale parameter） when the ITRF combine solution is constructed.The linear hypothesis of the ITRF construction leads to the current terrestrial reference frame only at the cm-level,which cannot satisfy the requirements of monitoring mm-level crust movements as well as the global environment.This article points out that the construction of a mm-level Terrestrial Reference Frame is actually a leap from linear to nonlinear.Therefore,according to the main characteristics of nonlinear changes of the crust＇s deformation,the geocenter motion and the overall height fluctuation of the Earth,the new ITRF station coordinates definition and the new observation equations of combined solutions are constructed for the realization of a mm-level nonlinear ITRF,which can solve the problems of the current ITRF.

关 键 词：International Terrestrial Reference Frame geocenter motion SCALE linear to nonlinear definition of ITRF station coordinates the coordinate transformation expression 

分 类 号：P228.4[天文地球—大地测量学与测量工程] X511[天文地球—测绘科学与技术]