Abstract
Abstract. Tropospheric delay has always been an important issue in Global Navigation Satellite System (GNSS) processing. Empirical tropospheric delay models are difficult to simulate complex and volatile atmospheric environments, resulting in poor accuracy of the empirical model and difficulty in meeting precise positioning demand. In recent years, some scholars proposed to establish real-time tropospheric product by using real-time or near-real-time GNSS observations in a small region, and achieved some good results. This paper uses real-time observing data of 210 Chinese national GNSS reference stations to estimate the tropospheric delay, and establishes ZWD grid model in the country wide. In order to analyze the influence of tropospheric grid product on wide-area real-time PPP, this paper compares the method of taking ZWD grid product as a constraint with the model correction method. The results show that the ZWD grid product estimated based on the national reference stations can improve PPP accuracy and convergence speed. The accuracy in the north (N), east (E) and up (U) direction increase by 31.8 %,15.6 % and 38.3 %, respectively. As with the convergence speed, the accuracy of U direction experiences the most improvement.
Highlights
Tropospheric delay has always been an important issue in Global Navigation Satellite System (GNSS) processing
The Zenith Total Delay (ZTD) is usually expressed as the sum of hydrostatic and non-hydrostatic parts, i.e., Zenith Hydrostatic Delay (ZHD) and Zenith Wet Delay (ZWD) (Davis et al 1985)
The GMF model was used for the mapping function of ZHD and ZWD, and gradient correction was introduced to correct for the gradient effect in the horizontal direction of the tropospheric delay
Summary
Tropospheric delay has always been an important issue in Global Navigation Satellite System (GNSS) processing. Empirical tropospheric delay models are difficult to simulate complex and volatile atmospheric environments, resulting in poor accuracy of the empirical model and difficulty in meeting precise positioning demand. This paper uses real-time observing data of 210 Chinese national GNSS reference stations to estimate the tropospheric delay, and establishes ZWD grid model in the country wide. The results show that the ZWD grid product estimated based on the national reference stations can improve PPP accuracy and convergence speed. This paper constrains the true coordinate of stations to improve the accuracy of real-time PPP troposphere estimation. The results show that the realtime tropospheric delay product can significantly improve the accuracy of real-time differential, and accelerate the convergence of real-time PPP. Compared with the plane direction, the convergence performance of elevation direction is improved even greater
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