Research On The Model Of Ground-Based GPS Of Tomography Three-Dimensional Atmospheric Water Vapor

Water vapor is an important part of the atmosphere, which is the main driving force for weather and climate change and plays an important role in the small-scale severe weather formation and evolution process. Therefore, to obtain high-precision, high spatial and temporal resolution of atmospheric water vapor distribution information is particularly important for weather forecasting, climate monitoring and disaster prevention and mitigation. Ground-based GPS technology for the detection of atmospheric water vapor provides a new method, which has a low cost, high spatial and temporal resolution, high precision, all-weather operation, high efficiency and many other advantages, effectively compensates for the shortcomings of conventional atmospheric detection means. This thesis uses the partial data of Sichuan CORS network to carry out the experiment of three-dimensional tomography of atmospheric water vapor, the main contents are summarized as follows:(1) The key problems of ground-based GPS tomography of three-dimensional atmospheric water vapor are discussed, including the calculation of tropospheric zenith wet delay, selection of mapping function and determination of the weighted average atmospheric temperature. In the case of tomographic equations may occur rank-defect, the Kalman filter algorithm without additional constraints is used to solve tomographic equations.(2) The effect of uniform and non-uniform vertical stratification method on the tomographic results have been studied, experimental results show that the tomographic results by the non-uniform vertical stratification is better than the uniform vertical stratification, but also more in line with the actual distribution of atmospheric water vapor.(3) Studied the uniform grid model, the non-uniform grid model and the extended grid model on the results of tomography. The results show that the tomographic water vapor density profiles of three kinds are consistent with sounding water vapor density profile, the correlation coefficient is reached or close to 0.99; the non-uniform grid model relative to the uniform grid model can improve the water vapor density of tomographic internal area, the higher spatial resolution and the number of unknowns is reduced; compared with the tomographic results of non-uniform grid model, extended grid model did not improve the accuracy of boundary grid tomographic results, but extended grid model to some extent can improve the overall results of tomography water vapor, so that the rationality of the grid model was verified.(4) Analyzed the characteristics of the spatial distribution of water vapor and the variation with time by combining with three-dimensional distribution of water vapor, the time sequence diagram of water vapor profiles and the cross-section of water vapor which obtained by tomographic experiments.