关键词: GNSS, PPP, 对流层延迟, 拟合模型

Abstract: Tropospheric delay is a significant error source in precise point positioning (PPP).To enhance PPP accuracy and reduce convergence time,fitting modeling of tropospheric delay in relevant regions can be performed to provide users with high-precision atmospheric parameter corrections.Addressing the limitations of traditional polynomial tropospheric delay models—which primarily consider mathematical approximation,neglect physical variations,and exhibit poor fitting performance in regions with significant elevation changes,this paper proposes an improved optimal fitting coefficient method based on a composite exponential function to model the height variation of tropospheric delay.This aims to enhance PPP performance over large areas and regions with substantial elevation variations.The results demonstrate that compared to the traditional optimal fitting coefficient model,the improved model enhances tropospheric delay accuracy across different station height intervals by 18.4%,19.5%,and 37.5%,respectively.In dynamic PPP mode,incorporating this model reduces the convergence time in the height component by an average of 20minutes.The new model demonstrably enhances both tropospheric delay accuracy and convergence speed.

Key words: GNSS, PPP, tropospheric delay, fitting model