Research On Application And GNSS Tropospheric Delay Correction

Tropospheric delay is one of the main error sources in GNSS positioning.It is of great importance to weaken the tropospheric delay for high-precision GNSS positioning.In addition to improve the precision and the reliability of GNSS positioning,tropospheric delay with high precision can be used to retrieve atmospheric water vapor.Ground-based GPS technique has become one of the critical techniques to retrieve atmospheric water vapor,playing an important role in disastrous weather forecast,such as,heavy rainfall and rainstorm.Therefore,it is of great significance to research the atmospheric precipitation using ground-based GPS and its application in weather variations.The main task and results are summarized as follows:1.ZTD from IGS sites are computed respectively by the models of GPT2 and GPT2 w and then the precision of two models are verified.The influence of GPT2 w on the coordinates precision of CMONOC are analyzed.Result shows that bias of vertical component is the largest of all.Then,the relationships among vertical component,height and latitude are analyzed.Result shows the distribution of vertical component accords with that of terrain of China,that is,vertical component increases with the inceasing of height from east to west;The relationship between vertical component and latitude is unsteady in Chinese mainland.2.The influence of difference of atmospheric parameters between GPT2 and GPT2 w on difference of ZTDs is analyzed.Result shows that the difference of less than one in atmospheric parameters results in that of 6 mm in ZTD.Then,the difference between atmospheric parameters and the difference between ZTDs are analyzed respectively from the perspective of spatial-temporal.It can be concluded that as for GPT2 and GPT2 w,the difference between ZTDs depends largely on the difference between atmospheric parameters of vapor pressure,and that seasonal feature appears on both.3.Three mapping functions are analyzed from the aspect of modelling principle.Based on the three mapping functions,precise point positioning is conducted and the influence of mapping functions on precise point positioning is analyzed.As for the characteristics in northeast Asia,the influence of season on the difference of mapping functions is analyzed and result shows that the difference of mapping functions vary with season.4.A method of regional CORS network parallel augmentation based on un-difference model is proposed.The parallel computing of FCB estimating,tropospheric delay estimating and modelling is finished,shortening the time of CORS network augmentation service.As for static observations,the positioning precision are,respectively,improved by 16.1%,8.8% and 40.1% in the east,north and vertical components,especially,in the vertical components.As for the static hourly solutions,the positioning precision are improved by 90.4%,72.7% and 32.4% in the east,north and vertical components,respectively,especially,in the east components.5.Based on weighted mean temperature from GPT2 w,atmospheric precipitation is retrieved,the precision of which is comparable with that of atmospheric precipitation based on weighted mean temperature by Bevis equation.The influence of weighted mean temperature with systematic correction on atmospheric precipitation is analyzed.Result shows that weighted mean temperature with systematic correction has little influence on atmospheric precipitation.Atmospheric precipitation is retrieved based on troposphere augmentation information,the precision of which is comparable with that of atmospheric precipitation based on troposphere estimating.