Research On The Key Technology Of Joint InSAR/BDS Inversion Of Atmospheric Water Vapor

Water vapor is one of the most active components of the atmosphere and is an important part of the atmosphere that affects weather conditions and precipitation,so monitoring the spatial and temporal changes of atmospheric water vapor is of great importance for disaster weather forecasting research and economic development.Traditional atmospheric water vapor detection methods such as radiosonde water vapor radiometer,and global navigation satellite system are able to determine atmospheric water vapor changes and strongly promote the development of meteorology.However,these observation means are mainly station measurements,which have the problems of fewer stations and uneven distribution,and none of them has the ability to observe atmospheric water vapor with continuous and complete coverage in space.Moreover,the construction and maintenance of ground stations are very difficult under extreme natural conditions.Meteorological observation satellites mainly detect atmospheric water vapor through infrared band or near-infrared band,which can monitor a wide range of atmospheric water vapor information,but it is greatly affected by weather conditions and difficult to monitor small changes in atmospheric water vapor information.InSAR is a geodetic tool developed rapidly in the past 30 years,with all-day,all-weather earth observation capability,and its interferometric phase map is obtained by subtracting the phase values of corresponding pixels of two/multiple images covering the same area at different moments,which has achieved important applications in atmospheric water vapor inversion studies.However,the atmospheric phase in the interferometric phase map is the difference in the propagation path of the two electromagnetic wave signals in the atmosphere caused by the changes in atmospheric conditions(temperature,humidity,air pressure,wind speed and electron density,etc.)at the moment of the two SAR images,which is a relative measurement result with respect to the reference image and reference point,and there are problems of calibration correction and reliability assessment.bds is a global satellite navigation system developed by China itself,which can precision measurement of atmospheric precipitable water and has the advantage of high temporal resolution measurement.Therefore,combining the advantages of spatially continuous atmospheric water vapor inversion by InSAR and temporally continuous atmospheric water vapor inversion by BDS is expected to achieve the complementary advantages of atmospheric precipitable water inversion by the two techniques.In this thesis,based on the basic theories and methods of InSAR and BDS inversion of atmospheric precipitable water,a joint InSAR/BDS inversion of precipitable water vapor is carried out using a variety of meteorological observation data.On the one hand,BDS satellite observation data,GPS satellite observation data and meteorological sounding station data are used for the inversion study of atmospheric precipitable water,and on the other hand,the spatially continuous atmospheric precipitable water vapor is obtained by combining InSAR,BDS and ERA5 meteorological reanalysis data.The main research contents and conclusions are as follows:(1)BDS atmospheric water vapor inversion method and accuracy analysis study.Using the original observation data of a provided by Shandong Provincial Institute of Land Surveying and mapping and the WUHM precision ephemeris released by Wuhan IGS,the BDS PWV was obtained by inversion based on GAMIT software.Using the 2020 meteorological sounding station observation data,the sounding station PWV is obtained based on the numerical integration method;using the GPS satellite observation data in September2020,the GPS PWV is obtained by inversion;the European Center for Medium-range Weather Forecasts(ECMWF)provides the ERA5 PWV in September 2020 for comparison and analysis:the average deviation between BDS PWV and sounding station PWV in 2020 is around The average deviation of BDS PWV from GPS PWV for six CORS stations in Shandong Province is less than 1.05 mm,and the average deviation of BDS PWV from ERA5 PWV is less than2.26 mm.(2)InSAR inversion of precipitable water vapor.A total of 33 scenes of Sentinel-1A data from 2020 to 2021 are used to generate 38 pairs of differential interferograms for atmospheric water vapor inversion experiments.The spatial distribution of tropospheric dry delay is obtained by calculating the phase of tropospheric dry delay using the surface pressure from the ERA5 meteorological reanalysis data released by the European Center for Medium-range Weather Forecasts,and the accuracy of ERA5 tropospheric dry delay is verified.The resolution of the dry delay component and the differential interferogram are unified by using the bilinear interpolation method,and the phase of wet delay associated with atmospheric water vapor in the differential interferogram phase is extracted.The water vapor conversion coefficients are constructed using temperature,potential and pressure data from ERA5 meteorological reanalysis data,and the accuracy of water vapor conversion coefficients is verified by comparison.The bilinear interpolation method unifies the resolution of water vapor conversion coefficients and differential interferogram,and the InSAR PWV(relative value)is obtained from the tropospheric wet delay phase and water vapor conversion coefficients.(3)Joint BDS/InSAR inversion atmospheric correction and validation study.the InSAR technique obtains the relative PWV content at a certain moment,and requires external high-precision data to spatially and temporally correct the InSAR PWV data.The spatial correction is completed by using BDS PWV to calibrate InSAR PWV(relative value),and InSAR/BDS ?PWV is obtained.comparing InSAR/BDS ?PWV with BDS ?PWV,the average deviation is 0.14 mm,and for the two validation reference stations,the average deviation is0.09 mm and 0.13 mm,respectively.using BDS PWV data to construct atmospheric The spatial distribution information(absolute value)of water vapor is used to complete the correction in time,and the spatially continuous and temporally continuous absolute value of precipitable water vapor is obtained by combining InSAR/BDS ?PWV with the initial spatial distribution information of water vapor.The average deviation is 1.47 mm when comparing InSAR/BDS PWV with ERA5 PWV.