| The Study on Present-day Crustal Movement and Deformation on the Basis of Global Positioning SystemPh.D. Candidate: Meng GuojieAdvisor: Prof. Lu Zuoli &Prof. Gu Guohua(Institute of Geophysics, China Seismological Bureau) (Center for Analysis and Prediction, China Seismological Bureau)AbstractOn the basis of the raw data of GPS surveying of Crustal Movement Observation Network of China (CMONOC), the influences of different schemes of GPS data processing on baseline repeatability are discussed. The models of wet atmospheric delay are analyzed and the precision of GPS observations is discussed with different expression methods. Regarding the problems of current global plate movement models, the author has proposed a method to construct new models with Space Geodesy data. Starting from the definition of terrestrial reference system, the methods of constructing and maintaining of modern terrestrial reference frame are introduced. The features of ITRF97 are discussed and their net rotations are calculated. In addition, the characteristics of crustal movement and deformation in China are studied on the basis of GPS survey carried out in recent years.According to the above methods and approaches, research work is made on the following aspects: ?schemes of data processing of large scale GPS monitoring network; (2) construction of the model of recent global plate movement; (3) methods of construction and maintenance of modern terrestrial reference frame; ?Characteristics of crustal movement and deformation in China detected by GPS surveying in recently years.The conclusions of this thesis are as follows:(1) After the comparison and analysis of 4 schemes of processing the data of large scale GPS monitoring network, the author propose a new good scheme of GPS data processing. It is thought that, with reference to the latest terrestrial reference frame, sufficient IGS stations with high quality and simultaneous surveying should be selected to unify with regional stations, and their data should be processed together, so that regional network and global network can be strongly tied. The GLORG module should be used to choose the reference stations in the combined adjustment with GLOBK program. This step can not only get the final result with reference to ITRF, but also make results stable.(2) The best representation of atmospheric wet zenith delay can be specified as a first-order Gauss-Markov process. It is quit necessary to pay much attention to set the parameters of Gauss-Markov process T, which, represent correlative time parameter.Usually, T should be about 3000 times larger than the time interval, not too small and not infinite, so that the wet zenith delay can be modeled correctly. Piecewise linear method can improve the repeatability in E-W component, height component and baseline length. But it can't improve apparently the repeatability of NS component. Unreasonable shortening the interval of estimating wet delay parameter can't improve effectively baseline repeatability, and the computation time will be much longer with the increasing number of unknowns.(3) The surveying precision of the first epoch observation of the fiducial stations and basic stations of CMONOC is good. The repeatability of daily solution is as follows: 4mm for N-S component, less than 8mm for E-W component, and less than 15mm for height component. After combined adjustment, the coordinate precision of horizontal component is 2-3 mm and the precision of height is 3-5mm. The repeatability of N-S component, E-W component, U-D component and length of baseline are 3.3mm, 5.3mm, 7.5mm and 4.3mm respectively. The relative precision of baseline is 10"9 in average. According to the similarity transformation of combined solutions of two adjacent weeks, the displacement precision is about 2.0 mm. With reference to ITRF97, the velocity error is less than 5mm within 95% confidence level.(4) The short-term repeatablity and long term repeatablity reflect the influences of different factors. Since the errors of sat...
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