The precise point positioning real-time kinematic (PPP-RTK) is a high-precision global navigation satellite system (GNSS) positioning technique that combines the advantages of wide-area coverage in precise point positioning (PPP) and of rapid convergence in real-time kinematic (RTK). However, the PPP-RTK convergence is still limited by the precision of slant ionospheric delays and tropospheric zenith wet delay (ZWD), which affects the PPP-RTK network parameters estimation and user positioning performance. The present study aims to construct a PPP-RTK model augmented with a priori ZWD values derived from the global forecast system (GFS) product (a global numerical weather prediction (NWP) model) to improve the PPP-RTK performance. This study gives a priori ZWD values and conversion based on the GFS products, and the full-rank GFS-augmented undifferenced and uncombined (UDUC) PPP-RTK network model is derived. To verify the performance of GFS-augmented UDUC PPP-RTK, a comprehensive evaluation using 10-day GNSS observation data from three different GNSS station networks in the United States (US), Australia, and Europe is conducted. The results show that with the GFS ZWD a priori information, PPP-RTK performance significantly improves at the initial filtering stage, but this advantage gradually decays over time. Based on 10-day positioning results for all user stations, the GFS ZWD-augmented PPP-RTK approach reduces the average convergence time by 46% from 10.0 to 5.4 min, the three-dimensional root-mean-square (3D-RMS) error by 5.7% from 3.5 to 3.3 cm, and the time to first fix (TTFF) value by 35.8% from 6.7 to 4.3 min, all when compared to the traditional PPP-RTK without GFS ZWD constraints.

精密单点定位实时运动（PPP-RTK）是一种高精度全球导航卫星系统（GNSS）定位技术，结合了精密单点定位（PPP）广域覆盖和实时快速收敛的优点。时间运动学 (RTK)。然而，PPP-RTK收敛仍受到倾斜电离层延迟和对流层天顶湿延迟（ZWD）精度的限制，影响PPP-RTK网络参数估计和用户定位性能。本研究旨在构建一个 PPP-RTK 模型，并增强来自全球预报系统（GFS）产品（全球数值天气预报（NWP）模型）的先验 ZWD 值，以提高 PPP-RTK 性能。本研究给出了基于GFS产品的先验ZWD值和转换，并推导了全秩GFS增强非差分非组合（UDUC）PPP-RTK网络模型。为了验证 GFS 增强 UDUC PPP-RTK 的性能，使用来自美国、澳大利亚和欧洲三个不同 GNSS 站网络的 10 天 GNSS 观测数据进行了综合评估。结果表明，利用GFS ZWD先验信息，PPP-RTK性能在初始滤波阶段显着提高，但这种优势随着时间的推移逐渐衰减。基于所有用户站10天的定位结果，GFS ZWD增强的PPP-RTK方法将平均收敛时间从10.0分钟减少到5.4分钟，三维均方根（3D-RMS）误差减少了46%与没有 GFS ZWD 约束的传统 PPP-RTK 相比，从 3.5 厘米到 3.3 厘米，首次定位时间 (TTFF) 值缩短了 35.8%，从 6.7 到 4.3 分钟。