Abstract
Abstract. The recent dramatic development of multi-GNSS (Global Navigation Satellite System) constellations brings great opportunities and potential for more enhanced precise positioning, navigation, timing, and other applications. Significant improvement on positioning accuracy, reliability, as well as convergence time with the multi-GNSS fusion can be observed in comparison with the single-system processing like GPS (Global Positioning System). In this study, we develop a numerical weather model (NWM)-constrained precise point positioning (PPP) processing system to improve the multi-GNSS precise positioning. Tropospheric delay parameters which are derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis are applied to the multi-GNSS PPP, a combination of four systems: GPS, GLONASS, Galileo, and BeiDou. Observations from stations of the IGS (International GNSS Service) Multi-GNSS Experiments (MGEX) network are processed, with both the standard multi-GNSS PPP and the developed NWM-constrained multi-GNSS PPP processing. The high quality and accuracy of the tropospheric delay parameters derived from ECMWF are demonstrated through comparison and validation with the IGS final tropospheric delay products. Compared to the standard PPP solution, the convergence time is shortened by 20.0, 32.0, and 25.0 % for the north, east, and vertical components, respectively, with the NWM-constrained PPP solution. The positioning accuracy also benefits from the NWM-constrained PPP solution, which was improved by 2.5, 12.1, and 18.7 % for the north, east, and vertical components, respectively.
Highlights
As the first space-based satellite navigation system, Global Positioning System (GPS) consisting of a dedicated satellite constellation has been extensively applied for many geodetic applications in the last decades
The European Centre for Medium-Range Weather Forecasts (ECMWF) zenith total delay (ZTD) for 34 globally distributed stations from the International GNSS Service (IGS) Multi-GNSS Experiments (MGEX) network during September 2015 are validated by the official IGS ZTD products which are provided with a temporal resolution of 5 min
The ECMWF ZTDs are represented by black triangles, while the IGS ZTDs are displayed by red squares
Summary
As the first space-based satellite navigation system, Global Positioning System (GPS) consisting of a dedicated satellite constellation has been extensively applied for many geodetic applications in the last decades. Li et al (2015a) developed a foursystem (GPS + GLONASS + Galileo + BeiDou) positioning model to fully exploit all available observables from different GNSS They demonstrated that the fusion of multiple GNSS showed a significant effect on shortening the convergence time and improving the positioning accuracy when compared to single-system PPP solutions. Hobiger et al (2008a) made use of ray-traced slant total delays derived from a regional NWM for GPS PPP within the area of eastern Asia They demonstrated an improvement of station coordinate repeatability by using this strategy in comparison to the standard PPP approach where the tropospheric delays were estimated as unknown parameters. We develop a NWM-constrained PPP processing method to improve the multi-GNSS (a combination of four systems: GPS, GLONASS, Galileo, and BeiDou) precise positioning.
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