基于多模PPP-AR技术的大气水汽探测性能分析

Performance analysis of atmospheric water vapor detection based on multi-constellation PPP-AR technology

精密单点定位(precise point positioning, PPP)反演大气可降水量(precipitable water vapor, PWV)具有精度高、实时性强等优点,能够在灾害监测、降雨预报及探测降水信息等方面发挥重要作用。为评估整周模糊度固定模式下PPP-AR(PPP ambiguity resolution)反演PWV的性能,选取全球范围16个MGEX站2022年4个时段的观测数据,采用最终精密星历解算,设置不同星座组合(GPS,BDS-3,GPS+BDS-3,GPS+GLO+GAL+BDS-3)获取对流层延迟(zenith total delay, ZTD)估值,并转换为PWV。从PPP-ZTD与IGS-ZTD的相关性、PPP-ZTD收敛时间、ZTD估值精度和PPP-PWV估值精度4个方面评价多模PPP-AR探测水汽的性能。结果表明,与单(G、C)、双系统(GC)固定解相比,多系统(GREC)固定解获取ZTD估值更加精确,相关系数更高。相较于单、双系统,多系统具有更快的收敛速度,收敛时间分别缩短了27%,25%和20%,多系统固定解与浮点解相比收敛时间缩短11%。此外,对GNSS PPP反演的PWV与探空站PWV(RS-PWV)进行对比,结果表明,WUH2站与HOB2站单、双、多系统固定解、多系统浮点解(float-GREC)的平均均方根误差分别为6.40 mm, 6.48 mm, 6.19 mm, 6.17 mm, 6.19 mm和5.82 mm, 5.77 mm, 5.72 mm, 5.62 mm, 5.70 mm。多模下得到的PWV估值精度最高,可为高精度的水汽反演提供支持。

Precise point positioning(PPP)to retrieve precipitable water vapor(PWV)has the advantages of high accuracy,strong real-time performance,and can play an important role in terms of disaster monitoring,rainfall forecasting and detecting rainfall information.In order to evaluate the performance of PPP ambiguity resolution(PPP-AR)inversion of PWV,observation data from 16 MGEX stations around the world for four periods in 2022 are selected,and the final precise ephemeris is used for calculation,and different constellation combinations(GPS,BDS-3,GPS+BDS-3,GPS+GLO+GAL+BDS-3)are set to obtain zenith total delay(ZTD)valuation and the inversion of PWV.The water vapor detection performance of multi-constellation PPP-AR is evaluated from four aspects:the correlation between PPP-ZTD and IGS-ZTD,the convergence time of PPP-ZTD,the estimation accuracy of ZTD and the estimation accuracy of PPP-PWV.The results show that compared with single(G,C)and dual system(GC)fixed solutions,the multi-constellation(GREC)fixed solution obtains ZTD estimation more accurately and has a higher correlation coefficient.Compared with single and dual systems,the multi-constellation has faster convergence speed,and the convergence time is shortened by 27%,25%and 20%respectively.The multi-constellation fixed solution has a convergence time shortened by 11%compared with the floating-point solution.In addition,the comparison of PWV and Radiosondes PWV(RS-PWV)retrieved by GNSS PPP shows that the mean root mean square errors of the single system(G,C),dual system(GC),multi-constellation fixed solution(GREC)and multi-constellation floating-point solution(float-GREC)of the WUH2 station are 6.40 mm,6.48 mm,6.19 mm,6.17 mm,6.19 mm,respectively;and those of the HOB2 station are 5.82 mm,5.77 mm,5.72 mm,5.62 mm and 5.70 mm,respectively.The PWV estimation accuracy obtained in multi-constellation is the highest,which can support high-precision water vapor inversion.