The method of zenith path delay (ZPD) estimation based on precise point positioning (PPP) is introduced. Besides,the effect of various factors on ZPD estimation' s accuracy is analyzed from the view of mapping function selection, satellite cut-off elevation angle setting, the use of precise ephemeris and clock errors. Accordingly, relatively better mode and data processing strategy are determined. Large amount of experiments and analysis show that ZPD with relatively high accuracy can be obtained by use of both NMF and GMF, and the difference between them is little. Moreover, 5° - 10° in the cut-off elevation angle is more favorable to ZPD estimation. In addition, the ZPD calculated with rapid precise ephemeris and clock errors or with predicted precise ephemeris and rapid precise clock errors are of the similar accuracy as that derived from post precise ephemeris and clock errors. However, accuracy of ZPD obtained by adopting extrapolated ultra-rapid precise ephemeris and rapid clock errors slightly decreases but is still relatively high.%介绍利用精密单点定位(PPP)技术进行天顶对流层延迟(ZPD)估计的方法,从投影函数模型选取、卫星截止高度角设置、精密星历与精密钟差的使用3方面分析了各种因素对天顶对流层延迟估计精度的影响,确定了相对较优的模型和数据处理策略.大量的算例和分析表明:采用NMF与GMF均可获得较高精度的ZPD,二者差异甚小;采用5°～10°的截止高度角更利于得到较好的ZPD结果;采用快速精密星历和钟差、实时观测精密星历和快速精密钟差解算的ZPD结果与采用事后精密星历和钟差的精度是相当的,而采用外推超快精密星历和快速精密钟差解算测站ZPD值的结果精度稍有下降,但仍具较高的精度.
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