The Research Of Atmospheric Correction Method For GB-InSAR

For many years,geological disasters such as landslides and subsidence have endangered people's lives and property.The GB-InSAR technology,with the characteristics of high space-time resolution and high deformation monitoring accuracy,has been widely utilized on slope deformation monitoring in recent years.Many scholars have studied GB-InSAR technology,but there are still many problems that restrict the accuracy of GB-InSAR.Among these problems,atmospheric disturbance has the greatest impact on the monitoring accuracy of GB-InSAR.Therefore,this graduation dissertaiton systematically studies the problem of atmospheric disturbances in GB-InSAR;on the basis of analyzing the existing solutions,the corresponding atmospheric correction models and time-series processing methods are proposed for their deficiencies.The specific work is as follows:(1)The traditional atmospheric correction method is based on the assumption spatial homogeneity for atmospheric medium;under this assumption,this dessertation proposes an atmospheric correction method based on the wrapped phase by analyzing the mathematical model of atmospheric phase.The atmospheric delay coefficient is calculated by establishing the model based on the range difference and phase difference of high-quality points.Compared with the traditional method,this method can calculate the atmospheric delay coefficient without phase unwrapping,which simplifies the operation,the possible phase unwrapping error could be avoided.(2)Traditional atmospheric correction method calculates the atmospheric delay coefficient by establishing function model of phase and range based on selected high-quality points.However,during the measurement of GB-InSAR,due to the influence of extreme weather,such as wind or turbulence,the assumption is sometimes hard to guarantee,which becomes a thorny problem in GB-InSAR atmospheric correction.In order to solve this problem,two-dimensional atmospheric correction model based on polar coordinate system and three-dimensional atmospheric correction model based on rectangular coordinate system are proposed respectively,considering the unhomogenety on different azimuths in a small range and the unhomogenety in each direction on three-dimentional space for big range caused by extreme weather.The experiments show that the accuracy of GB-InSAR atmospheric correction is improved by proposed model.(3)In GB-InSAR,due to the long observation time and large amount of data,the time baseline is usually enlarged,resulting in the problems,such as slight time decorrelation,the difficulty of phase unwrapping and severe atmospheric disturbance.The traditional PS-InSAR in space-borne InSAR can solve these problems well,but the characteristics in terms of phase composition and atmosphere of GB-SAR and spaceborne SAR data are quite different.Therefore,this paper introduces the traditional spaceborne PS-InSAR method and improves it based on the characteristics of GB-SAR data.A time series analysis method considering atmospheric correlation in time is proposed,and the GB-SAR data collected in Malanzhuang is used for validation.