Research On Atmospheric Water Vapor Effect And Content Retrieval In InSAR Height Measurement

Interferometric Synthetic Aperture Radar(InSAR)technology plays an important role in terrain mapping,surface deformation monitoring with its outstanding advantages such as fast,all-weather,high resolution.However,in the development of repeat-pass InSAR technology,the SAR signal will delay by the atmospheric effect,especially the atmospheric water vapor with rapid changes in time and space.The height error caused by atmospheric water vapor up to tens of meters,deformation measurement error up to decimeter.In order to quantitatively study the influence of atmospheric water vapor and research the water vapor retrieval method with InSAR data,this thesis has researched the influence rule of water vapor on InSAR height measurement and the atmospheric water vapor retrieval method using InSAR technology,the main work and innovations of the thesis include:1.The research status of the influence of atmospheric water vapor on InSAR elevation measurement and water vapor content retrieval are analyzed.The background and advantages of InSAR and the development of InSAR technology are introduced.The formulas about influence of atmospheric water vapor on InSAR elevation measurement and DInSAR deformation monitoring is deduced.The research status and existing problems of atmospheric water vapor impact correction and water vapor inversion are introduced.2.A simulation scheme on verifying the effect of atmospheric water vapor on the InSAR height measurement is designed,and the influence of atmospheric water vapor is studied quantitatively under different parameters.Using stripe mode imaging parameters and baseline parameters,the scheme simulates water vapor effect interferogram refering to the DEM and vertical layered water vapor model and calculates elevation.On the other side,set the water vapor content,the baseline length and the incident angle as a single variable to analyze the water vapor effect law,and provide the theoretical basis for atmospheric water vapor correction.3.The influence of different atmospheric water vapor distribution on InSAR height deriving is studied.In order to study the effect of different distributions of water vapor on the accuracy of repeated orbital InSAR measurement and the correction effect of baseline estimation on the systematic error,this paper simulates the water vapor model with different distribution patterns,then interferometric process with the main and auxiliary SAR data.According to statistical analysis of control point elevation error,the influence of different water vapor distribution characteristics on InSAR height measurement was studied.The experimental results show that the uniformity of the water vapor is similar to the system noise,and the baseline estimation has an error assignment function,but it cannot weaken the uneven distribution of water vapor.4.A method of water vapor content retrieval by repetitive orbital InSAR image is proposed.First interferogram is processed with two groups of SAR data without surface deformation,then simulate terrain phase using DEM in radar coordinate system according to the image parameters and the baseline parameters,finally remove simulated terrain phase from the interference phase and filter the remaining phase to get high-resolution and continuous atmospheric water vapor content.The characteristics of water vapor changes have an important predictive effect on the rainfall occurrence and development in the study area.The experimental results show that the SAR data with short time interval and good coherence can invert high resolution and continuous water vapor content,which is of great significance to the understanding and prediction of high precision meteorology.