不同饱和水汽压模型对GNSS反演可降水量的影响分析

Analysis of influence of different saturated water vaporpressure models on GNSS inversion precipitable water

地基全球卫星导航系统(GNSS)水汽反演过程中需要大气加权平均温度Tm的参与,而饱和水汽压Es作为Tm计算过程中的一个重要变量影响着Tm,因此Es将会间接地影响大气可降水量(PWV)的反演精度.针对目前地基GNSS水汽反演研究中普遍采用的三种不同的饱和水汽压模型(Magnus-Tetens模型、BUCK模型、Goff-Gratch模型),本文就不同的饱和水汽压模型参与反演是否会引起水汽反演结果的差异进行了研究.以香港为研究区域,利用GAMIT解算了2016年旱雨两季(2、7月)的天顶湿延迟(ZWD),同时利用king’s park探空站的探空数据通过数值积分计算得到旱雨两季(2、7月)的Tm,然后严格参照反演步骤编程模拟计算旱雨两季(2、7月)每天的PWV.最后对比并分析了不同饱和水汽压模型参与计算对Tm和PWV的影响及原因,结果表明:三种饱和水汽压模型参与计算得到的PWV与真值(探空站计算得到的PWV)之间不存在具有统计意义的显著性差异,因此均可被用来提供计算Tm时所用到的饱和水汽压Es,但是通过对比分析发现部分研究人员将BUCK模型中的变量T当作露点温度而非大气温度进行计算会使Tm产生较大的误差,进而对该误差进行了不合理性分析.本文的分析将会对后续地基GNSS水汽反演研究中的处理提供一定的参考.

Atmospheric weighted mean temperature(T m)participation is required for ground-based GNSS water vapor inversion,and saturated water vapor(E s)is an important variable in the calculation process of T m that effects T m,so e swill be indirectly affect the inversion accuracy of Precipitable Water Vapor(PWV).In view of the three saturated water vapor pressure models(Magnus-Tetens model,BUCK model,Goff-Gratch model)established by different researchers commonly used in the research of ground-based GNSS water vapor inversion,this paper will research different saturated water vapor pressure models participate in the inversion Whether cause differences in results.Taking Hong Kong as the research area,using GAMIT to solve the Zenith Wet Delay(ZWD)of the dry and rainy season(February and July)in 2016,meanwhile using the sounding data of the King's park sounding station to calculate The T m of the dry and rainy seasons(February and July)through the way of integrate numerical,and then calculating the PWV of the dry and rainy seasons(February and July)through programing with reference to the inversion steps.Thorough comparing and analyzing to get the effects and reasons of different saturated water vapor pressure models participating in the calculation on T m and PWV.The results show that between the PWV calculated by the three saturated water vapor pressure models and the true value(PWV calculated by the sounding station)have no statistically significant differences,so all of them can be used to provide the saturated water vapor pressure e s in the calculation of T m,However,through comparative analysis,it is found that some researchers use the variable T in the BUCK model as the dew point temperature instead of the atmospheric temperature to make T m produce a larger error.The analysis in this paper will provide a certain reference for the treatment of T m in the subsequent research of ground-based GNSS water vapor inversion.