Application Research Of InSAR Tropospheric Delay Correction

One of the main errors affecting the accuracy of InSAR monitoring is atmospheric delay.For short-wavelength microwaves,it is generally important to study tropospheric delay and ignore ionospheric delay.There are a variety of tropospheric delay correction methods available,but the existing calibration methods have their own scope and defects,and it is important to determine which calibration method to use based on the terrain.Based on this outstanding problem,this paper took "comparative analysis of tropospheric delay correction methods under different terrain conditions" as the overall research direction,and analyzed the influence of troposphere on electromagnetic wave and InSAR measurement accuracy.The principles of time series InSAR method,meteorological information modeling method and GACOS method are emphasized.The experimental and quantitative analysis of the atmospheric phase in the spaceborne repeat orbit InSAR is carried out,and the application strategy of the tropospheric delay correction method is proposed.This study collected 26 sentinel data from September 28,2016 to August 18,2017 in Yuanbaoshan District,Chifeng City,and 18 sentinel data from March 15,2017 to October17,2017 in Maoxian County,Aba Tibetan and Qiang Autonomous Prefecture,Sichuan Province.These data were processed,and the atmospheric correction was performed by time series InSAR method,meteorological information modeling and GACOS method.Using the interferogram phase statistical characteristics for comprehensive analysis,the conclusions are as follows::(1)In Yuanbaoshan District,the interferograms which were performed by the time series InSAR method,meteorological information modeling method and GACOS method accounted for 100%,36.2% and 72.3% of the all 47 interferograms,respectively.In the Maoxian area,the interferograms which were performed by the time series InSAR method,meteorological information modeling method and GACOS method accounted for 100%,37.2% and 65.1% of the all 43 interferograms,respectively.The results show that the timeseries InSAR method is superior to the meteorological information modeling method and the GACOS method from the perspective of reliability.The GAOCS method is superior to the meteorological information modeling method.If a sufficient number of SAR images can be obtained,the sequential InSAR method is preferred.(2)The meteorological information modeling method and the GACOS method can effectively remove the vertical stratification delay associated with the terrain,but when the turbulent mixing delay dominates the atmospheric delay,the two methods may introduce correction errors.Therefore,when sufficient SAR images cannot be acquired,atmospheric correction can be performed using the meteorological information modeling method or the GACOS method,but it is necessary to check each interference pair one by one.(3)The combined technical flow of GACOS and time series InSAR method is proposed.The results show that in the Maoxian area,the 28 interferograms were subjected to atmospheric correction by the time-series InSAR method,GACOS method and the combined correction method.The phase standard deviations were reduced by 31.7%,17.12% and 46.3%,respectively,indicating that it is better to use the combination of the two to correct the atmospheric delay.