Strain Rate Inversion Based On Large-scale GNSS Network

With the large-scale establishment of continuously operating reference stations,GNSS has been more and more applied to deformation monitoring and strain inversion.The integration of existing GNSS data processing software and strain rate inversion function is not high,which is not conducive to high-precision GNSS deformation monitoring of high aging and rapid analysis of strain rate inversion.Based on the high-precision data processing technology of large-scale GNSS network,this paper studies the GNSS data processing strategy,the pre-processing method of GNSS coordinate time series and the strain rate inversion algorithm,and develops the strain rate inversion system based on large-scale GNSS network,which has reference significance for the realization of automatic strain rate rapid inversion.The main research contents are as follows:1.based on the noise characteristics of ultra-high sampling rate data and the Modified Geometry-Free(MGF)combination,a low-latency cycle slip determination method is proposed for GNSS data,named OMGF.This paper deduces the success rate of OMGF cycle slip repair for pseudorange and carrier phase observations with different noise levels for different satellite systems,and the observation noise boundary conditions for OMGF method.The experiment results with 20 Hz measurements show that,the success rate of OMGF method is about 99.998%.Compared with the combination of GF and HMW,OMGF method is about60 times faster.2.Strain rate field inversion system based on large-scale GNSS data network was developed.Based on the existing GNSS data processing system,the BDS data processing module was optimized,and the automatic acquisition of parameter information,network adjustment and strain rate inversion modules were added to realize automatic data processing in multiple periods.3.The calculation accuracy of CORS station data test system for 182 days around Los Angeles was used.The results with show that the coordinate time series of the self-developed system is in good agreement with the coordinate time series provided by SPOAC.The external coincidence precision of all directions is millimeter level,with the minimum of 1.99 mm and the maximum of 4.35 mm.Based on 60 CORS stations in Sichuan Province,the strain rate distribution characteristics of Sichuan Province are inversion.The results show that the southern part of the Bayan Kala block and the Sichuan Basin mainly show compression deformation,while the northeastern part of the Sichuan-Yunnan rhomboid block mainly shows expansion deformation.The shear strain rate near Xianshuihe and Anninghe fault zones is obviously higher than that of other regions,and the crustal tectonic instability near the fault zones is strong.