Real-time Inversion Of Atmospheric Water Vapor Using Ground-based GNSS Technology

With the rapid development of ground-based GNSS meteorology,atmospheric water vapor Inversion based on GNSS plays an indispensable role in the field of meteorology.How to achieve high accuracy and high timeliness is a problem faced by GNSS-PWV.Therefore,this paper studies the theory and method of GNSS-PWV technology,mainly analyses the flow chart and error source of real-time precise point positioning,and studies the theoretical model of water vapor inversion.By using the real-time recovered orbit,clock,standard meteorological parameters and Bevis atmospheric weighted temperature model,real-time PPP-PWV supporting system is realised based on VS2010.The program is validated by sounding data and networking technology results.The main contents of this paper are as follows:(1)The basic theory of GNSS meteorological technology and two commonly used models--network solution and precise point positioning--are introduced in detail.Firstly,the atmospheric composition,stratification and the dry and wet components in the troposphere are introduced in detail.Secondly,GNSS positionging and error sources are studied.Finally,the inversion results of two technical models,double-difference network solution and non-difference network solution,are compared,and the results show that the inversion accuracy of the two schemes is basically the same.(2)Using the real-time orbit and clock correction data stream released by IGS,the orbit and clock accuracy of real-time recovery are experimentally analyzed,and the feasibility of real-time recovery of orbit and clock for real-time precise point positioning is verified.(3)Various prior formulas for calculating atmospheric weighted temperature are introduced,and the precise values calculated from sounding data are used as benchmarks to verify the high applicability of Bevis prior formulas in the global scope.(4)By calculating different stations for solving the problem of parameter setting in data processing,and the optimal parameter settings scheme is determined.According to the optimized parameters,the observation data of Hong Kong CORS network from 2017 to 2018 are calculated,and the accuracy of PWV inversion and the periodic variation of PWV in Hong Kong are analyzed by comparing the radio sounding data as a benchmark.(5)According to the theory of real-time precise point positioning and water vapor inversion,a real-time PPP-PWV program is programmed based on C/C++.Experiments in different periods are carried out,and the accuracy of the program is verified by comparing with the results of network solution and post-processing PPP.