Research On Ground-based GPS Water Vapor Inversion Based On EGNOS Model

Atmospheric precipitation is one of the main components of the earth's atmosphere.Many natural disasters and weather changes are closely related to it.Therefore,how to accurately monitor water vapor is a key issue in meteorology.However,ordinary water vapor detection methods have many disadvantages.Ground-based GPS technology has advantages such as high spatio-temporal resolution.Compared with traditional detection methods,the process and characteristic analysis of strong convective weather is more accurate and clear.Taking the Hong Kong region of China as an example,this paper studies the time and space distribution of water vapor in Hong Kong based on ground-based GPS data.At the same time,several different levels of precipitation in Hong Kong were used to analyze the changes of water vapor before and after rainfall,and to study the relationship between water vapor and rainfall.The main research contents and conclusions of the paper are as follows:(1)Selection of troposphere model.Analyze and compare several tropospheric delay models with the tropospheric delay values calculated from sounding data as true values,including three meteorological parameter models(Saastamoinen model,Hopfield model,and Black model)and two non-meteorological parameter models(UNB3 model and EGNOS)Model),and combined with the mapping function,calculate the tropospheric delay value in any direction.It was found that the non-meteorological parameter model EGNOS is closest to the sounding value and can be used as the tropospheric delay model in Hong Kong.(2)Establishment of atmospheric weighted average temperature model.Atmospheric weighted average temperature is another important content of this study after the tropospheric delay.By performing daily mean processing on the atmospheric weighted average temperature and performing single-factor modeling and multi-factor modeling at 02:00 and12:00,it is found that the single-factor model is superior to the multi-factor model.Among single-factor models,the Tm-Ts daily mean model fits best.Through comparison and analysis with atmospheric weighted average temperature models established by other scholars,it is found that the Tm-Ts model established in this paper can effectively eliminate some errors and has the highest accuracy.(3)Inversion of GPS PWV in Hong Kong.GAMIT software was used to calculate thetotal tropospheric zenith delay.In the solution process,four IGS stations evenly distributed around Hong Kong were added to constrain.In the selection process of IGS stations,not only one domestic station was added,but three foreign IGS were added at the same time.Station,the purpose is to improve the accuracy of GAMIT solution.After calculating the total zenith delay,a series of work was performed to obtain the water vapor value in Hong Kong.The accuracy analysis and comparison of ground-based GPS PWV and the calculated sounding PWV show that the ground-based GPS PWV is consistent with the sounding PWV in time,and the accuracy is equivalent to sounding.(4)Analysis of the precipitation characteristics of GPS PWV in Hong Kong.By analyzing the characteristics of ground-based GPS inversion of water vapor before and after three different levels of precipitation in Hong Kong,we can find that no matter what rainfall intensity,during the period before the rainfall began,the amount of atmospheric precipitation began to increase significantly.After the precipitation,the water vapor value stabilizes.Prediction of precipitation can be made in advance through the PWV trend of ground-based GPS inversion.