The Research On The Theory And Method Of Maintenance And Renewal Of CGCS2000 Reference Frame

The definition,renewal and maintenance of high-precision Terrestrial Reference Frame(TRF)has always been an international hot issue.In recent years,many countries and regions have been studying and implementing the modernization and renewal of local geodetic reference coordinate frames.China Geodetic Coordinate System 2000(CGCS2000)has been employed since July 1,2008.Along with the sustained economic and social development,national defense construction,scientific research and the globalization of the applications of COMPASS global navigation satellite system(BDS),China has proposed new requirements for the accuracy,stability,and globalization of the CGCS2000.Based on the precise results of the high-precision CORS network and the large-scale GNSS network,this paper focuses on the key technologies of renewal and maintenance of geocentric coordinate framework,establishes the complete theoretical system and effective implementation method for the accuracy realization,dynamic analysis and stability maintenance of CGCS2000 and provides a complete theoretical system and effective implementation methods for the globalization of the CGCS2000.The main research results are as follows:1)The data from the continuous observation of the CORS network from 1999 to 2016 and from the multi-period repeated observation of the large-scale GNSS network from 1999 to 2013 are finely processed,obtaining the coordinates and velocities in the Chinese mainland with the highest precision(coordinate accuracy better than 5 mm,velocity better than 2mm/a),the widest range(covering the Chinese mainland),and the highest density(1664 points).2)The selection principles of global and regional coordinate reference frame stations are studied.The seven parameter method,supervised classification and hierarchical rasterization method are applied to make reasonable and rigorous analysis of the selection of the global frame sites.The effective connection between the CGCS2000 and ITRF frame lays the foundation for the globalization of the CGCS2000.3)The method of constructing the velocity field of the current crustal movement in the Chinese mainland is studied.The model of crustal deformation velocity field of high spatial and temporal resolution under the CGCS 2000 frame is built base on the adoptions of the Finite Element Interpolation method.The vertical velocity field of the regional crustal movement is established and the regional crustal deformation characters of the Chinese mainland are analyzed.4)The non-structural deformation of the crust caused by the mass loading effect is studied and analyzed.The International Earth satellite data and geophysical models are used to correct the impact of the mass loading effects on the position time series of CORS stations.And then,a spatial filtering algorithm based on Principal Component Analysis is employed to extract the Spatial-temporal characteristics of Common Mode Errors(CME).Finally,quantitative analysis of the impact of non-structural deformation on the CGCS2000 is made and a nonlinear motion reference frame in the Chinese mainland is constructed.5)Wavelet analysis,spectral method and noise analysis method are implemented to analysis stability of CORS and the noise characteristics of the coordinate time series generated from CORS.It is suggested that white noise is not the main part of the noises in the coordinate time series of CORS network in China,while the white noise,flicker noise and random walk noise are the basic characteristics in the coordinate time series of CORS network.6)For the first time,the theory of colored noise has been introduced into the velocity estimation and actual accuracy assessment of the CORS stations in the Chinese mainland.The maximum likelihood method is used to quantitatively estimate the colored noise components in the coordinate residual time series.The weighted least squares method is used to evaluate the velocity estimation and the actual accuracy of CORS network with different noise effects under the CGCS2000.7)The mathematical model for the construction of the Global CGCS2000 is studied.The theory and algorithm of the Global CGCS2000 built with the inner constraints theory is analyzed to prove that under certain conditions the two-step method and one-step method are equivalent.This research result can improve the basic theoretical framework of coordinate frame determination,and provide scientific methods for the globalization of the CGCS2000.8)The constraint conditions of coordinate reference are redefined according to the minimum standard of frame transition parameters and its rate variation.Inner constraints algorithm is studied and the adjusted network is obtained through coordinate similarity transformation.As a result,the adjusted network enjoys the highest degree of fitting to the shape of the initial network and the inherent purity of the coordinate network using different observation technologies can be maintained to ensure that the advantages of different observation technologies can be brought into full play.