Establishment And Application Of Regional Zenith Tropospheric Delay Model

Tropospheric delay is one of the main factors affecting GNSS navigation and positioning accuracy.The general method to eliminate tropospheric delay error is to use tropospheric delay model for correction.At present,the commonly used empirical models are built for the global or large area,and there are large systematic errors in the use of small area,and some tropospheric correction models need meteorological data.Today many provinces and cities have set up CORS system,which is widely used in many fields by virtue of its advantages of real-time,all-weather,high spatial-temporal resolution.In this paper,the observation data of CORS network in Henan Province are solved by using GAMIT software,and the regional tropopause delay correction model which only needs time and location parameters is established for Henan region.On this basis,ARIMA model is used for single CORS station compensation correction and applied to the inversion of regional atmospheric precipitable water vapor.The main research contents are as follows:(1)The temporal and spatial variation characteristics of tropospheric zenith delay in Henan are analyzed.The experimental results show that Henan tropospheric zenith delay has obvious annual periodic single peak variation in time distribution,and in terms of spatial distribution,the tropospheric zenith delay has an approximately negative exponential relationship with the station elevation.(2)Based on the analysis of the temporal and spatial variation characteristics of tropospheric zenith delay in Henan Province,a regional tropospheric zenith delay model without meteorological parameters is established.The average accuracy of tropospheric zenith delay estimated by the new regional model is about 2cm,which is better than that of the traditional EGNOS model,and the correction accuracy is improved by about 2-3 times.(3)For a single CORS base station,an ARIMA compensation model is established to improve the error of the newly-built regional tropospheric zenith delay model.The accuracy of ARIMA compensation model is about 1cm,and the actual fluctuation of tropospheric zenith delay can be estimated in detail.(4)Based on the meteorological data of Nanyang sounding station,the single-factor and multi-factor models of atmospheric weighted average temperature suitable for Nanyang area are established.The experimental results show that the accuracy of two models are better than that of empirical Bevis model,and the accuracy of multi-factor model is slightly better than that of single-factor model.(5)The atmospheric precipitable water vapor(PWV)in Nanyang area is calculated by the newly-built tropospheric zenith delay model and ARIMA compensation model combined with the single factor model of atmospheric weighted average temperature,and take Radio-PWV as the reference value to evaluate the accuracy.The results show that the root mean square error of the inverted PWV is 4.7mm,the mean average absolute error is 3.6mm,and the trend of the prediction curve is basically consistent with the reference value.In the absence of measured meteorological parameters,it has a certain practical reference value to use this method to invert PWV in Nanyang area.