基于GPS精密单点定位(PPP)技术,比较分析了水平梯度及目前三种主要的映射函数(NMF,VMF1和GMF)对天顶对流层延迟(ZTD)估计精度的影响。研究结果表明,在气象变化剧烈和低高度截止角情况下,附加水平梯度的对流层延迟模型有利于提高ZTD精度;就映射函数效用而言,VMF1和GMF较NMF更优。
Based on GPS Precise Point Positioning(PPP) technology,this paper analyzed the influence of horizontal gradients and three main mapping functions(NMF,VMF1 and GMF) on the accuracy of zenith tropospheric delay(ZTD) estimation.The numerical results show that adding horizontal gradients to tropopheric delay model will improve the ZTD precision when the weather changes dramatically or the cut-off angle of observations is low.As to the effectiveness of mapping functions,VMF1 and GMF are better than NMF.