| Over 20 years,the GPS observation data accumulated by global IGS base stations and CORS(Continuously Operating Reference Stations)systems of all levels have provided valuable data base for scientific research in geodesy and geodynamics.Especially,it has played an important role in analysis of regional crustal deformation,dictation of strong earthquake field,research on silent slip event,analysis of global plate model and postglacial adjustment and so on.However,the coordinates of these sites obtained by conventional GPS data processing usually contain non-construction noises,thus it is important to study the characteristics and sources of the noises,which would be helpful in reducing the amount of the noises,promoting the implementation of study work in regional fault slip and earthquake forecasting.Therefore,in this way,it is a significant value in science and application.Based on 6-years CORS data in Shenzhen from 2010 to 2015,this paper is mainly about the coordinate time series processed by softwares---GAMIT/GLOBK and PANDA.After learning from the research results from predecessors,this paper has applied several ways to study the characteristics and sources of the non-construction noises in GPS coordinate time series.The specific research contents are as follows.1.The principle and method of GPS coordinate time series analysis are introduced in detail.This paper describes several commonly used methods of time series analysis,including power spectrum analysis,maximum likelihood estimation,regional stacking filtering,principal component analysis and KLE,and then compares their advantages and disadvantages.2.GNSS processing Softwares named GAMIT/GLOBK and PANDA are used respectively to handle the Shenzhen CORS data of 6 consecutive years.The results show that the accuracy of single-day solution of two GPS data processing softwares can reach millimeter level.The principle,computing process and accuracy of two softwares are analyzed in detail,and then the obtained coordinate time series is preprocessed.3.Analyzing the characteristics of Shenzhen CORS coordinate time series.The influence of different noise models on the evaluation of various parameters of the series is analyzed by using a variety of methods in several perspectives.The common mode error(CME)of the SZCORS stations is extracted by the principal component spatial(PCA)filtering method.The parameter estimations of the series are computed and compared before and after the filtering.Moreover,the influence of the surface mass loading on the series is calculated,and the origin of the periodic component in U direction is analyzed.The optimal noise model of Shenzhen CORS is established,and thus the velocity field of Shenzhen CORS stations is constructed.The crustal deformation pattern in Shenzhen is explored preliminarily.4.The characteristics of time series from IGS stations in mainland China and surrounding areas i analyzed based on the series products of different organizations.The results show that there is a slight difference between the results of the different institutions,but they are at the same level overall.The distribution of white noise and flicker noise has a strong difference between sea and land,and stations close to ocean have greater white noise and flicker noise than inland stations.The content of colored noise after PCA filtering is decreased,and the velocity distribution of IGS stations in mainland China is acquired based on the parameter estimation of WN + RW + FN noise model. |
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