Research On Ground-based Beidou/GPS Atmospheric Water Vapor Retrieval And Its Application

Atmospheric water vapor is an important part of the atmosphere,and its temporal and spatial changes and content are affected by factors such as temperature,climate,and terrain.Weather phenomena and natural disasters on the earth are all affected by atmospheric water vapor.Therefore,effective and accurate monitoring of water vapor with high temporal and spatial resolution has important practical value and practical significance for forecasting and early warning of disaster weather and guiding the development of the national economy.Compared with conventional water vapor monitoring methods,ground-based GNSS remote measurement technology has the advantages of high accuracy and high temporal and spatial resolution.With the dense arrangement of GNSS ground observation networks,it has become one of the indispensable methods for traditional detecting atmospheric water vapor.On July 31,2020,Beidou-3 global satellite navigation system with independent intellectual property rights formed a global coverage and service capability.The performance analysis based on the Beidou satellite to detect atmospheric water vapor is crucial to the application of the Beidou global navigation system to global water vapor detection.The experimental data sources used in this thesis includes the release of the Multi-GNSS experimental project MGEX,the Shandong Continuous Operating Reference Stations(SDCORS)provision and the high-precision GNSS observation data of the single CORS station of the Shandong Jianzhu University.On the one hand,based on the high-precision GNSS observation data,the software GAMIT10.72 is used to carry out the atmospheric precipitation water vapor inversion experiment;on the other hand,the tomographic program is used to carry out the three-dimensional water vapor tomography experiment over Jinan area based on the tomographic input observation value of the Inclined path precipitation water vapor.The experiment uses radiosonde data as a reference value,uses the radiosonde data provided by the University of Wyoming and the U.S National Weather Data Center radiosonde data IGRA set for accuracy analysis and draws useful conclusions.The main research results of this thesis are as follows:(1)Based on the observation data released by the Multi-GNSS experimental project MGEX,the atmospheric precipitation water vapor can be retrieved,and the Beidou regional navigation satellite(Beidou-2,Beidou-2)and Beidou global satellite navigation(Beidou-3)The water vapor inversion results were compared with GPS inversion results and ERA5 grid data respectively,and the performance of Beidou-3 in global atmospheric water vapor detection was preliminary analyzed.The test results show that the performance of Beidou-3in detecting atmospheric water vapor is better than Beidou-2;in the Asia-Pacific region,Beidou-2 water vapor inversion results are consistent with GPS inversion results and ERA5 reanalysis data,which can meet the requirements of water vapor detection;Beidou-3 The performance of global detection of atmospheric water vapor is equivalent to that of GPS system,and the degree of dispersion and high degree of fit of the ERA5 water vapor product is small,and it meets the requirements of global water vapor detection.(2)Using the Beidou ultra-fast ephemeris(WHU)released by the IGS Data Center of Wuhan University to study the impact of the three mapping function models of NMF,VMF1 and GMF on the accuracy of atmospheric precipitation in the dry and wet seasons,and The water vapor inversion results of Beidou system were compared and analyzed with GPS system and ERA5 reanalysis data respectively to verify the accuracy and reliability of near real-time acquisition of Beidou/PWV.Experiments show that the accuracy of near real-time acquisition of Beidou/PWV in the Asia-Pacific region is comparable to that of GPS system and ERA5 water vapor products,with good consistency and high degree of fit.(3)Taking into account the geographical distribution of the 6 CORS stations in the SDCORS observation station network and the single CORS station of Shandong Jianzhu University,determine the appropriate horizontal and vertical resolutions in Jinan,and then determine the appropriate regional tomographic grid model Classification method;372radiosonde data from Zhangqiu radiosonde station(Zhangqiu,54727)in Jinan area are used to determine the optimal vertical height of the tomography of the study area,and the radiosonde height and wet refractive index are fitted to obtain the Gaussian of each month Function coefficient.(4)According to the three schemes of single-system GPS mode,single-system Beidou mode,and dual-system GPS+Beidou mode,the comparison and analysis with the vertical contour line of Zhangqiu radiosonde water vapor density verify the accuracy of the tropospheric tomographic water vapor results of the three schemes.(5)The NCEP reanalysis data set was used to calculate the four parameters of water vapor flux divergence,specific humidity,K index and vertical velocity during the chromatographic period,and to analyze the horizontal convergence and radiation of water vapor in the upper troposphere,airflow ups and downs,and atmospheric stratification stability before and after the rainfall in Jinan region on July 5,2020,and the water vapor density contour line of Beidou/GPS tomography is used to analyze the accumulation and transportation of water vapor.