Research On Inversion Of Atmospheric Precipitable Water Vapour By Ground-base GNSS

Compared with traditional water vapor detection methods,Global Navigation Satellite System(GNSS)has the advantages of all-weather,high precision,high temporal resolution and high spatial resolution.So using ground-based GNSS to retrieve water vapor has become a popular research direction in satellite navigation,positioning and meteorology.The Continuously Operating Reference Stations(CORS)can not only provide high-precision rapid positioning services,but also help in the regional water vapor inversion.However,due to the cost and other reasons,most of the domestic observation stations have not installed the relevant meteorological equipment,so the lack of meteorological data makes it impossible to directly obtain the PWV for the meteorological forecast.In view of this phenomenon,this paper analyzes and discusses the inversion method of PWV when there is no meteorological data.At last,the problems related to the inversion of PWV by the independently developed beidou satellite are studied.The main contents of this paper are as follows:(1)The principle of using sounding data to detect water vapor is introduced in detail,and the formula is realized by MATLAB.Three tropospheric models are used to calculate the statics delay and the conversion of the wet delay into water vapor.(2)Four IGS observation stations in China were selected to conduct GAMIT delayed tropospheric inversion,and the results of Zenith Total Delay(ZTD)released by CODE center were taken as the benchmark for comparison,which proved that GAMIT software can be used for high-precision ZTD inversion.(3)Three GNSS continuous observation reference stations containing meteorological instruments and three meteorological sounding stations in shaanxi were selected for the test.It is verified that the accuracy of water vapor inversion using GAMIT is higher than PIVOT,which is close to the sounding data.(4)Next,ten GNSS continuous observation reference stations containing meteorological instruments in shaanxi were selected for the test.Three tropospheric models,GPT3+Saastamoinen,GPT3+Hopfield and UNB3m,were selected to calculate the water vapor in the absence of meteorological data,and the results calculated by gamit-pwv were used as the benchmark for comparison.This paper analyzes which combination model can be used to calculate the water vapor with the highest accuracy,which is beneficial to the prediction of extreme weather.(5)Three GNSS observation stations and three sounding stations containing beidou data in shaanxi were selected for the test.The water vapor content was calculated by using three different big dipper calendar products provided by wuhan university,and the water vapor value detected by sounding data was used as the benchmark for comparison.The accuracy of water vapor obtained by three kinds of ephemeris is analyzed,and the weather forecast can be carried out by using the part of the ultra-fast ephemeris forecast.