地基GPS反演大气可降水量方法的改进  

Improvement on the Method for Estimating Precipitable Water from Ground-based GPS

作　　者：徐桂荣[1] 万蓉[1] 李武阶[1] 陈波[1] 冯光柳[1] 

机构地区：[1]中国气象局武汉暴雨研究所,武汉430074

出　　处：《暴雨灾害》2009年第3期203-209,共7页Torrential Rain and Disasters

基　　金：中国气象局武汉暴雨研究所暴雨研究开放基金(IHR2007G01);中国气象局武汉暴雨研究所科研业务项目(0803);湖北省气象局科技发展基金(2007Z03);国家自然科学基金(40575011)共同资助

摘　　要：利用地基GPS反演大气可降水量(PW,precipitable water)的方法中,GPS PW的准确度依赖于天顶静力延迟(ZHD,zenith hydrostatic delay)的计算模型和转换系数П。分析Saastamoinen模型、Hopfield模型、Black模型计算的ZHD误差发现,其计算的ZHD与探空ZHD相比具有模型偏差,这些模型偏差换算成对GPS PW的影响约为4～10 mm。通过回归建模,对Saastamoinen模型、Hopfield模型和Black模型中的系数进行修正后,可明显减小这些模型偏差,且不影响这些模型的精度。转换系数П是大气加权平均温度(Tm,atmospheric weighted mean temperature)的函数,Tm与地面温度(Ts)高度相关,根据这一特性,利用9个探空站数据通过回归建模得到的Tm本地化模型可很好地拟合Tm,其模型均方差为2.8 K,对应的相对误差为1.0%。对地基GPS反演PW的方法进行改进后,求得的GPS PW的系统偏差明显减小,其中,采用改进的Hopfield模型和Tm本地化模型求得的GPS PW,与探空廓线计算的PW相比,其偏差为-1.6 mm,而与微波辐射计廓线计算的PW相比,其偏差为-1.2 mm。In the method for estimating precipitable water（PW） from ground-based GPS,the accuracy of GPS PW depends on the zenith hydrostatic delay（ZHD） model and the parameter П.Through the error analysis on the ZHD calculated by Saastamoinen,Hopfield,and Black models,it is found that the modeled ZHD has a system bias from the ZHD calculated from radiosonde profiles,corresponding to a bias of 4～10 mm on GPS PW.The system bias of Saastamoinen,Hopfield,and Black models can be reduced by correcting the model coefficients with a regression method,with few effects on the system root-mean-square error.The parameter П is a function of atmospheric weighted mean temperature（Tm）,and Tm has a strong linear correlation with surface temperature（Ts）.According to the high correlation between Tm and Ts,a local Tm model is constructed by a linear regression based on radiosonde observing profiles at 9 observatories,with a root-mean-square error of 2.8 K,corresponding to a relative error of 1.0%.Adopting the modified ZHD model and the local Tm model,the system bias of GPS PW is reduced.Compared with PW calculated from radiosonde profiles,the GPS PW estimated with the modified Hopfield model and the local Tm model has a bias of-1.6 mm,while compared with PW calculated from radiometer profiles,the bias of GPS PW is-1.2 mm.

关 键 词：地基GPS 可降水量 天顶静力延迟 天顶湿延迟 大气加权平均温度 

分 类 号：P414.4[天文地球—大气科学及气象学]