Research On Tropospheric Delay Correction Method Of SAR Interferometry In Land Subsidence Monitoring

In recent years,the rapid identification and prediction of disasters in areas with high geological disasters have received great attention from the national level.Synthetic Aperture Radar Interferometry(InSAR)is capable of high-precision monitoring of large-scale surface deformations around the clock and all the time,providing a new means for the identification of surface subsidence.However,in the case of large monitoring areas and complex terrain,its It is seriously affected by time-space decoherence and atmospheric delay,and the atmospheric delay changes periodically with the seasons,which also makes the traditional spatio-temporal filtering method unable to accurately estimate and correct the deviation of atmospheric delay,and the monitoring accuracy is relatively low.Time series InSAR technology breaks through this limitation.Based on this,this paper uses sentinel-1 A data to analyze the suppression method of tropospheric delay,aiming to improve the accuracy and reliability of InSAR technology in wide area surface deformation monitoring.The main research contents of this article are as follows:(1)The principle and advantages and disadvantages of atmospheric delay correction in repeated orbit InSAR technology are analyzed.The distribution characteristics of InSAR tropospheric delay were analyzed using sentinel-1A data.From the results,the tropospheric delay is related to the terrain.Where the terrain is more undulating,the phase of the tropospheric delay in the interferogram is more complicated.(2)In order to reduce the influence of the tropospheric delay on the interferometric measurement results and improve the accuracy of InSAR measurement,this paper improves a time series InSAR analysis method.Based on the conventional time series InSAR technology,the differential interference atlas after removing the terrain is first phase unwrapped,and the unwrapping result is interferometrically superimposed to estimate the linear deformation rate of the study area.The rate results are used as the reference threshold range for the deformation rate during time series regression analysis.Iterative regression analysis is used to finally extract high-precision deformation results.The deformation information of 22 scenes of ALOS-2 PALSAR(spatial resolution:3 meters)from August 2016 to October 2017 in Huangtupo landslide in Badong County,Enshi City,Hubei Province was analyzed,and the deformation history of the test area was analyzed.This result is verified by the accuracy of leveling point and PS-InSAR method,which proves the effectiveness and accuracy of the method for deformation monitoring.(3)Use the method of this paper to invert the surface deformation of Hubei Province from 2017 to 2018 The difference index is used to select points,and the point target extraction results are fused,and the phase analysis is performed in a unified manner,and finally a map of the provincial surface stability survey in Hubei Province is generated.Through the analysis of historical geological disasters and field investigation and verification,as well as cross-validation with ALOS-2 data with strong penetration and high resolution,the effectiveness of the proposed method in the correction of atmospheric delay errors in wide-area surface deformation monitoring is verified Sex.