In precise point positioning (PPP), the zenith hydrostatic delay (ZHD) is traditionally treated as a priori value from the ZHD model but the zenith wet delay (ZWD) is treated as an unknown parameter to estimated. For some near real-time PPP tasks, priori ZHD from the blind ZHD models are often used because external meteorological measurement or information about atmospheric pressure or ZHD can not be obtained in such conditions. On the other hand, a priori ZHD errors can project into GNSS height estimates errors in the PPP analysis, because unmodeled part of the ZHD is usually absorbed into the estimated ZWD while there is the difference between the hydrostatic mapping function and the wet mapping function. In this study, we found the errors of the ZHD seasonal models are not always less than those of the ZWD seasonal models, which implies that the traditional strategy for treating ZTD (priori ZHD and estimated ZWD) is not always the best choice when using the blind zenith tropospheric delay (ZTD) models. A decision model for the ZTD blind model (DMZBM), which is a new strategy of dealing with ZTD in PPP when using blind ZTD models, was proposed. For most cases, the traditional strategy works while for some exception cases, it is recommended that priori ZWD from the blind ZWD model was set but ZHD is treated as an unknown parameter to estimated. The DMZBM can directly reduce ZHD–ZWD mutual absorption errors which potentially reduce GNSS height estimates errors due to the difference between the hydrostatic mapping function and the wet mapping function. The results show that there are significant reductions of ZHD–ZWD mutual absorption errors in polar regions when using the new ZTD-treating strategy.

中文翻译：

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减少盲ZTD模型用户的ZHD-ZWD互吸收误差

在精确点定位（PPP）中，传统上将天顶静液压延迟（ZHD）作为ZHD模型的先验值，但将天顶湿延迟（ZWD）作为未知参数进行估计。对于某些接近实时的PPP任务，经常使用盲ZHD模型的先验ZHD，因为在这种情况下无法获得外部气象测量或有关大气压或ZHD的信息。另一方面，在PPP分析中，先验ZHD误差可能会投影到GNSS高度估计误差中，因为ZHD的未建模部分通常会吸收到估计的ZWD中，而静水绘图功能和湿测功能之间存在差异。在这项研究中，我们发现ZHD季节模型的误差并不总是小于ZWD季节模型的误差，这意味着使用盲天顶对流层延迟（ZTD）模型时，传统的ZTD处理策略（先验ZHD和ZWD估计值）并不总是最佳选择。提出了ZTD盲模型（DMZBM）的决策模型，该模型是使用盲ZTD模型处理PPP中的ZTD的新策略。对于大多数情况，传统策略有效，而对于某些例外情况，建议设置盲ZWD模型的先验ZWD，但将ZHD视为要估计的未知参数。DMZBM可以直接减少ZHD-ZWD的相互吸收误差，这可能会由于静水绘图功能和湿测功能之间的差异而潜在地减少GNSS高度估计误差。