Research Of Remote Sensing Atmospheric Precipitable Water Vapor By Ground-based GNSS

A close relationship is shown between water vapor a nd the formation of rainfall as well as climate change,despite its low content in the atmosphere.Water vapor is the key object of global climate monitoring,it also plays a significant role in balancing the atmospheric vertical stability and global earth system,etc.As a new cross-subject,GNSS Meteorology has a vast application prospect.It can not only improve the accuracy and spatiotemporal resolution of atmospheric water vapor content,but also reduces the cost of observation.It is of good benefit to study the basic principles and methods to inverse the water vapor content by ground-based GNSS stations,and it promotes the application in climatic prediction,weather forecast and so on.This paper analyses the advantages of the method which inverse the atmospheric water vapor by ground-based GNSS stations compared to the conventional techniques.According to the principles and computing methods based on GNSS water vapor remote sensing,an incorporate system design is raised,and the influence factors o n atmospheric water vapor estimation are analyzed.Furthermore,Aiming at the characteristic of local network,regional atmospheric weighted temperature model was established.For small regional network solver method and strategy are presented.The water vapor content was estimated with precise point positioning method and double difference of least squares method respectively.Double difference of kalman filter method can be used to real-time calculate water vapor in Ground-based GPS was verified with TRACK module.The result of calculation is verified by radiosonde and rainfall.The zenith tropospheric delay(ZTD)was calculated with BDS/GPS dual-mode data.And Beidou system for water vapor monitoring was proved to be feasible.The main work includes the following aspects:The conventional method of detecting atmospheric water vapor,the advantage of Ground-based GNSS technology,the classification of GNSS meteorology and its development at home and abroad application was introduced firstly.The main research contents of this dissertation are briefly described.(1)Common tropospheric delay model and the parameter estimation method was introduced.The principle of Ground-based GNSS detecting Atmospheric precipitable water vapor(PWV)was described.With high precision data processing software GAMIT,a set of system design scheme was proposed for Ground-based GNSS to real-time remote sensing atmospheric water vapor.The radiosonde was described to check the precision of Ground-based GNSS,which lay the foundation for analyzing the precision of GNSS-PWV.(2)Influence factors of Ground-based GNSS remote sensing PWV was analyzed.The precision of GNSS-PWV was verified.With radiosonde data and rainfall data in Zhengzhou and Wuhan,effects of long reference station number,coordinate limit,data processing mode,meteorological elements,satellite elevation cut-off angle,satellite ephemeris,the number of ZTD parameters,map function and gradient on the calculation of GNSS PWV were studied.Some experiences are summarized.(3)According to the Zhengzhou regional characteristics,the weighted mean temperature model was built.Zhengzhou region weighted mean temperature model was obtained by single factor(temperature ground Ts)and multivariate(Ts,ground water vapor pressure e,ground pressure Ps)linear regression method with Zhengzhou radiosonde data respectively.The RMS of region model is smaller than Bevis-Tm model when they were compared.RMS of Zhengzhou GNSS-PWV with the new model and radiosonde data is about 2.2mm,the distribution of two-dimensional PWV in Zhengzhou region was given.Double difference of least square method and PPP method to get difference of ZTD was analyzed,results show that the deviation is less than 1cm.(4)The TRACK module is introduced in this paper.A data processing scheme for real-time calculation of atmospheric water vapor content was put forward with TRACK.Double difference dynamic method based on Kalman filter,local region network monitoring station ZTD acquisition in real-time is realized.by comparison with the results of static GAMIT ZTD,the difference is less than 1cm,which verified the feasibility of using the double difference of dynamic Kalman filtering method to obtain real-time accurate PWV.The precision of PWV is better than 2mm.In addition,by analyzing the distribution of the rainy season China and numerical weather forecast,the importance of GNSS meteorology in weather forecasting was explained.finally,PWV changes was analyzed in Wuhan rainstorm examples.The feasibility Ground-based GNSS meteorology applied to weather forecast was verified.(5)Using BDS/GPS dual-mode data for precise orbit determination method are discussed.The global 18 stations ZTD was calculated with this method,The accuracy of GPS ZTD and BDS ZTD were compared,which RMS is less than 1cm.Then the results were compared by ZTD provided by CODE center.The BIAS is less than 1cm,RMS is better than 2cm.Finally,the precision positioning method and the precise orbit determination method was compared to calculate the ZTD.of solution of the accuracy of ZTD for the use of BDS,the next step in real time can provide the basic precipitation inversion,which provide the basis for remote sensing PWV with BDS.