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Abstract

The accurate knowledge of tropospheric delay plays a key role in the rapid precise positioning. However, the tropospheric delay map with high spatial and temporal resolutions cannot be obtained from Global Navigation Satellite System (GNSS) observations alone, which hinders its further improvement of positioning performance, especially under complex terrains. In this study, a tropospheric model which integrates Global Forecast System (GFS) analysis and forecast grids, GNSS tropospheric delays, and multi-source meteorological data is established based on the four-dimensional variational assimilation method, in order to augment the capabilities of GNSS PPP-RTK under the circumstance of mountainous areas. The proposed tropospheric model is capable of predicting tropospheric delays with a spatial resolution of less than 5 km. The accuracy of tropospheric delays derived from this model is evaluated by comparing with the ERA5 products. Also, the performance of the tropospheric model augmented PPP-RTK is investigated in terms of the success rate of ambiguity fixing, convergence time, and positioning accuracy. The results show that the proposed tropospheric model exhibits excellent capabilities in improving the precision of tropospheric delays as well as the PPP-RTK positioning performance.