Wide-area Rapid Tropospheric Tomography Adaptive Simultaneous Iterative Reconstruction Technique And Its Application

Water vapor plays a very important role in the earth 's atmospheric climate change,radiation balance,energy transportation,and cloud water formation.Therefore,high-accuracy and high temporal resolution water vapor information have a great significance for weather forecasting,hydrological monitoring,global climate change,resource remote sensing,geodetic survey and other fields research and application.With the development of GNSS meteorology,high temporal resolution three-dimensional water vapor information can be accurately obtained through ground-based GNSS observations and using tropospheric tomography.In this paper,we focus on the realization of wide-area three-dimensional rapid tomography,and develops a wide-area three-dimensional fast tomography system WATS.Then,through simulated data and measured data,we mainly study the impact of different factors on the tomographic results,the feasibility and accuracy of rapid tomography in Guangdong Province and China area.The main research work and results of this paper are summarized as follows:(1)In the study of tomography research,in order to avoid the influence of errors between different data sources on the evaluation of tomography results,therefore,by the WATS rapid tomography system developed in this paper,the SWD and meteorological observation are simulated based on the ERA5 reanalysis products,and the accuracy of the simulated data is evaluated.(2)In Guangdong province,based on simulated observations,the WATS system was used to discuss the impact of different factors on the tomography results.It's found that the meteorological observation can significantly improve the accuracy of the surface grid tomography results;With the addition of multi-system observations,there is no obviously change compared to single GPS system tomography results;While increasing the ground stations and the horizontal resolution of the grid,the tomography results can be improved to a certain extent.(3)In Guangdong province,based on the measured data,the tomographic experiments are carried out.In response to the "5-7" Guangzhou rainstorm event in 2017,the spatiotemporal change of wet refractivity from tomography results and the ZTD over the weather station are analyzed.The wet refractivity index extracted from the radiosondes and the SWD separated from the independent GPS station are used to evaluate tomography results.It is found that the accuracy of the tomographic products is higher than the wet refractivity filed information obtained by other means.(4)The simulation data of 1107 stations in China for one week proves the feasibility of rapid,verifies the internal accuracy of the tomography system,and finds the tomographic result of the eastern area with dense station is better than the western area with sparse station.(5)As for the Chine area tomography experiment based on measured data,SWD obtained from different data sources was compared.It is not ideal to use the stations distributed mostly in the eastern part of China to caculate SWD results mainly distributed in the central and western.Compared with the SWD generated based on the GFS and ERA5 background fields,it is found that because the tomography stations are mostly located in the eastern region,the SWD obtained from tomographic product perform better in the eastern region,which verifies the external accuracy of the tomography system.