对流层延迟与可降水量直接转换模型研究

采用线性回归和最小二乘法拟合建立无线电探空可降水量（RS-PWV）与GPS对流层延迟（GPS-ZTD）、地面温度及大气压之间的直接转换模型，并将直接转换模型得到的PWV分别与RS-PWV及GPS反演得到的可降水量（GPS-PWV）进行比较。结果表明，RS-PWV与GPS-ZTD之间存在良好的线性关系，相关系数达0.927 6；RS-PWV与4阶拟合温度和大气压呈现较好的相关性，相关系数分别为0.640 1和－0.626 3；基于ZTD的单阶单因子模型PWV与GPS-PWV的相关系数达到0.969 9；基于ZTD、温度及大气压的单阶多因子模型PWV比基于ZTD的单阶单因子模型PWV精度明显提高，RMS从4.3 mm提高到3.3 mm。

Study on the Direct Conversion Model Between Tropospheric Delay and Precipitable Water Vapor

There are problems in calculating conventional GPS precipitable water vapor (GPS-PWV), including the large amount of data, low efficiency, and many introduced observation errors. Based on the radiosonde and GPS data collected at Chenzhou CORS station in 2015 and using linear regression and least squares methods, a new direct conversion PWV model is established from radiosonde-derived PWV (RS-PWV), GPS tropospheric delay (GPS-ZTD), ground temperature and atmospheric pressure. The direct conversion PWV model is compared with RS-PWV and GPS-PWV respectively to verify accuracy and reliability. The correlation analysis shows a favorable linear relationship between RS-PWV and GPS-ZTD, with the correlation coefficient reaching 0.927 6. The RS-PWV has positive and negative correlation with the 4-order fitting temperature and atmospheric pressure; their correlation coefficient reaches 0.640 1 and －0.626 3 respectively. The correlation coefficient between single-order single-factor model PWV based on ZTD and GPS-PWV is 0.969 9, which shows the feasibility of directly calculating PWV from ZTD. The accuracy of single-order multi-factor model based on ZTD, temperature and atmospheric pressure is significantly higher than that of single-order single-factor model based on ZTD, and RMS is increased from 4.3 mm to 3.3 mm.Therefore, the accuracy of direct conversion PWV model is slightly lower than that of GPS-PWV, but it simplifies computation and improves efficiency.