Tropospheric delay is a crucial factor that limits precise point positioning (PPP) performance, especially at low altitude angles. Here, a remote sensing (RS)-augmented method was developed to improve PPP performance with high-quality zenith tropospheric delay (ZTD) derived from water vapor products of satellite GOES-18. The GOES-18 precipitable water vapor (PWV) was evaluated against the European Center for Medium-Range Weather Forecasts Reanalysis 5 (ERA5) PWV, with a root mean square error (RMSE) of 2.50 mm. The derived ZTD was validated using International GNSS Service (IGS) ZTD showing RMSE of 16.20 mm. Data from 42 GPS and GLONASS observed IGS stations were collected. The results show that the RS-augmented PPP improves convergence time and short-term precision in the vertical component for both GPS + GLONASS (G + R) and GPS-only compared to traditional PPP. For the G + R vertical component, the convergence time was shortened by 18.9% and the short-term positioning accuracy improved by 17.4%. For the GPS-only systems, the convergence time was shortened by 12.2% for the vertical components, while vertical component positioning accuracy increased by 19.5%. The 42 stations were categorized through different geographic conditions and atmospheric water vapor structures (ocean, coastline, and land) to analyze their convergence times and positioning accuracy. The results show that stations in ocean regions exhibited the greatest improvement in both convergence time and positioning accuracy. The improvement in convergence time was mainly related to the accuracy of the ZTD RMSE; the improvement in positioning accuracy was primarily influenced by the geographic conditions of the stations, such as station latitude.
Jia et al. (Wed,) studied this question.