Improving GNSS Precise Point Positioning with Numerical Weather Models

The recent dramatic development of GNSS (Global Navigation Satellite Systems) constellations brings great opportunities and potential for precise positioning, navigation, timing, and other applications. Precise positioning with the current Chinese BeiDou Navigation Satellite System is proven to be of comparable accuracy to the Global Positioning System (GPS), which is at centimeter level for horizontal components and sub-decimeter level for the vertical component. Significant improvement on positioning accuracy, reliability, as well as convergence time with the multi-GNSS fusion is demonstrated in comparison with the single-system processing like GPS. In this study, we develop numerical weather models (NWM) augmented precise point positioning (PPP) processing algorithms and investigate the effect of applying troposphere delay parameters derived from the short-range forecasts of Global Forecast System (GFS) of the National Centers for Environmental Prediction (NCEP) and the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis to BeiDou and multi-GNSS precise processing, respectively. Observations of stations from the International GNSS Service (IGS) Multi-GNSS Experiments network are processed, with the introduced NWM augmented PPP and the standard PPP processing. The accuracy of tropospheric delays derived from NCEP and ECMWF are assessed against with the IGS final tropospheric delay products. For Beidou processing, the results show that an improvement of convergence time up to 60.0 % and 66.7 % for the east and vertical components, respectively, can be achieved with the NWM augmented PPP solution compared to the standard PPP solution, while only slight improvement of the solution convergence is found for the north component. The positioning accuracy is improved by 38.6 %, 45.9 %, and 29.8 % for the east, north, and vertical components, respectively, with the NWM augmented PPP. For the multi-GNSS processing, the convergence time is shortened by 37.5 %, 32.0 %, and 25.0 % for the east, north, and vertical components, respectively, when performing the NWM augmented PPP compared to the standard PPP. The positioning accuracy also benefits from the NWM augmented PPP solution, which gets improved by 12.1 %, 2.5 %, and 18.7 % for the east, north, and vertical components, respectively.