To obtain better zenith hydrostatic delay (ZHD) corrections for global navigation satellite system (GNSS) applications, seven types of Vienna mapping function 1 (VMF1) and VMF3-like ZHD models provided by the Vienna University of Technology (TU Wien, TUW), University of New Brunswick (UNB) and GeoForschungsZentrum Potsdam (GFZ) are evaluated. Firstly, we find that the conventional method for implementing VMF1/VMF3-like ZHD models has issues when applied over regions with highly variable topography. Therefore, we propose an improved implementation method (called Trop_vertical) based on an empirical model as well as a second version, called Trop_vertical-II, which further corrects for small residual biases. The results show that the Trop_vertical-II can effectively reduce the large errors reported in previous studies for complex terrains and yields an improvement in global accuracy of up to 50% over the conventional method. Then, the multisource ZHD models are evaluated and intercompared globally. The results reveal some deficiencies with the TUW-VMF1 over certain regions. The newly developed ZHD models from the TUW (TUW-VMF3) and GFZ (GFZ-VMF3) both achieve reliable performances globally, but there is a systematic difference (~ 2.9 mm) between them. The forecast VMF1/VMF3-like models can well capture the rapid ZHD variation in challenging weather conditions. Finally, the impacts of a priori ZHD errors on both GPS-only and GPS/GLONASS precise point positioning (PPP)-based zenith total delay (ZTD) and height solutions are examined globally. The results suggest that the sensitivities of PPP-ZTD/height solutions to a priori ZHD errors decrease by adding GLONASS data at high latitudes but increase at low latitudes.

为了为全球导航卫星系统 (GNSS) 应用获得更好的天顶静力延迟 (ZHD) 校正，维也纳科技大学 (TU Wien, TUW) 提供的七种维也纳映射函数 1 (VMF1) 和类似 VMF3 的 ZHD 模型，新不伦瑞克大学 (UNB) 和 GeoForschungsZentrum Potsdam (GFZ) 进行了评估。首先，我们发现实现类 VMF1/VMF3 的 ZHD 模型的传统方法在应用于具有高度可变地形的区域时存在问题。因此，我们提出了一种基于经验模型的改进实现方法（称为 Trop_vertical）以及称为 Trop_vertical-II 的第二个版本，它进一步校正了小的残余偏差。结果表明，与传统方法相比，Trop_vertical-II 可以有效减少先前研究中报告的复杂地形的大误差，并使全局精度提高高达 50%。然后，在全球范围内对多源 ZHD 模型进行评估和比对。结果揭示了 TUW-VMF1 在某些区域的一些缺陷。TUW（TUW-VMF3）和GFZ（GFZ-VMF3）新开发的ZHD模型在全球范围内都实现了可靠的性能，但它们之间存在系统差异（~2.9 mm）。预测的 VMF1/VMF3 类模型可以很好地捕捉具有挑战性的天气条件下的快速 ZHD 变化。最后，先验 ZHD 误差对仅 GPS 和基于 GPS/GLONASS 精确点定位 (PPP) 的天顶总延迟 (ZTD) 和高度解决方案的影响在全球范围内进行了检查。