Precision Analysis of GGOS Tropospheric Delay Product and Its Application in PPP

doi:10.11947/j.AGCS.2017.20160383

Abstract

Abstract: The tropospheric delay is the main error source in satellite navigation, for which GNSS wide area augmentation needs ZTD product of high accuracy to correct error. The tropospheric delay can be simultaneously estimated by GNSS, and be also obtained from numerical meteorological forecast model based on multi-sources data. The global zenith tropospheric delay product published by IGS is resolved by GNSS, whose accuracy reaches 4 mm and time resolution is 5 minutes. However, the uneven-distributed IGS sites makes the vast ocean area without data coverage. Based on ECMWF re-analysis material for 40 years, GGOS Atmosphere provides global total zenith tropospheric delay grid data since 1979,whose time resolution is 6 h and spatial resolution is 2.5°×2°. The GGOS-ZTD product was assessed compared with ZTD material of global IGS sites in 2015 and the systematic difference between GGOS-ZTD and IGS-ZTD was researched.Systematic difference coefficients in every site (proportional error a and fixed error b) were estimated by linear fitting and then spherical harmonic expansion with a and b was made to build spherical harmonic expansion model for systematic difference coefficients (a and b).Finally the application effect of the GGOS Atmosphere ZTD product was analyzed with systematic difference eliminated in satellite navigation and positioning in IGS and CMONOC sites. The results prove that: there are systematic difference between GGOS-ZTD and IGS-ZTD. The mean bias is -0.54 cm and mean RMS of discrepancy is 1.31 cm, which is accurate enough to satisfy the ZTD correction needs of vast GNSS real-time navigation positioning users. The GGOS-ZTD product with its systematic difference corrected is used in the precise point positioning experiment in ALBH、DEAR、ISPA、PALM、ADIS、YNMH、WUHN sites. The result showed that the speed of convergence effectively is obviously advanced, especially in U direction(10.58%、31.68%、15.96%、43.89%、51.46%、14.69%、18.40% respectively).

Key words: ZTD, system error, spherical harmonic function fitting, PPP convergence speed

CLC Number:

P227

YAO Yibin, XU Xingyu, HU Yufeng. Precision Analysis of GGOS Tropospheric Delay Product and Its Application in PPP[J]. Acta Geodaetica et Cartographica Sinica, 2017, 46(3): 278-287.

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