Study On Tropospheric Delay Correction Using InSAR Monitoring Surface Deformation

InSAR technology is a new technology of space geodesy based on surface observation which has developed rapidly in recent years.However,InSAR technology is seriously affected by the tropospheric delay effect,which reduces the monitoring accuracy of InSAR technology itself and limits the application of InSAR technology in the field of high-precision surface deformation monitoring.This paper uses the 45 scene Sentinel-1A data,combined with SBAS-InSAR technology and MODIS water vapor products and GACOS atmospheric correction model to monitor the surface deformation of Panxian in Liupanshui City,Guizhou Province from January 2018 to July 2019.The time series analysis of the 12 mine goaf subsidence area detected in Panxian were carried out by comparing and analyzing the effects of the two atmospheric correction methods and the combination of the two methods in the research area.In order to verify the accuracy of Sentinel-1A time series InSAR monitoring results,the L-band ALOS-2 data was used to evaluate the accuracy of the monitoring results.The main research work and contents in this paper are as follows:(1)In view of the influence of tropospheric delay error on monitoring results in InSAR surface deformation,the mechanism of the influence of atmospheric water vapor in the troposphere on repeated orbit InSAR altimetry and D-InSAR monitoring deformation was emphatically analyzed.The specific manifestation of the tropospheric delay effect in the InSAR measurement results was introduced,which can be mainly divided into the effect of vertical layered delay and the effect of turbulent mixed delay.The two are different in the interferogram and the affected areas.When removing the atmospheric phase in the interferogram,the effects of the two should be considered separately.In addition,the method of tropospheric delay correction in InSAR measurement is summarized.(2)We use Sentinel-1A data covering 45 scenes of C-band in Panxian,Liupanshui City,Guizhou Provinceand and MODIS water vapor products and GACOS atmospheric correction model,MODIS+GACOS methods proposed in this paper to remove the atmospheric phase in the interferogram.Combined with time series InSAR technology we obtained the accurate surface deformation information in the study area.We selected the typical deformation region,and compared the average deformation rate of the study area obtained by time series InSAR combined with three different atmospheric correction methods MODIS,GACOS and MODIS+GACOS.The experimental results show that the accuracy of the MODIS method is increased by 2.3%,and the accuracy of the GACOS method is increased by 12.9%.Using the MODSI+GACOS method improves the accuracy by 20.5%.The results show that the combined method can remove atmospheric phase errors more effectively.(3)The accuracy of deformation monitoring results was verified from two aspects by using L-band ALOS-2 data:1)Determine whether the range of the deformation area and the deformation center point are consistent in the monitoring results of the two data sources.The results show that the deformation area ranges obtained by the two are relatively the same.The deformation range difference of point al is 0.26km2?point a7 is 0.1km2 and point a9 is 0.42km2,and the deformation center point position is basically the same.2)Judge whether the size of the deformation in the deformation area is consistent in the two data monitoring results,and compare whether the deformation value before and after removing the atmosphere has improved.The results show that the deformation values obtained by the two data sources have the same trend.The comparison of the average deformation rate between the three typical regions shows that the correlation at point al before removing the atmosphere/after is 0.54/0.68?a7 is 0.75/0.9 and the a9 is 0.64/0.84.In this paper,InSAR surface deformation monitoring was carried out in the typical deformation area of Liupanshui City,Pan County,Guizhou Province.More accurate surface deformation information was obtained by the correction of the tropospheric delay and combining the time-series InSAR technology.Through analysis and verification of the monitoring results,the more accurate deformation range and deformation amount in the study area are obtained,which provides an important judgment basis for preventing landslides and ensuring the safety of people's lives and property.