拉曼激光雷达测量水汽误差源分析研究

水汽与人类的生活息息相关。常规手段测量水汽的时空分辨率较低有效提高局地短期天气预报的可信度。为加强拉曼激光雷达在气象预报中的应用，有必要对其水汽测量误差进行分析研究。通过自研的拉曼激光雷达测量数据，依据误差传递理论，分析水汽混合比的误差。同时，利用无线电探空仪与拉曼激光雷达对比。分析结果表明：激光雷达测量水汽主要包括标定常数、大气透过率修正和测量信号三个误差源。其中，定标常数误差随高度不变约为4%，是1.5 km以下误差的主要来源；大气透过率修正误差随高度升高而增加，洁净天气下对误差的影响小于4%；测量信号误差在洁净天气下3 km高度以内一般小于20%，在3 km高度以上，成为误差的主要来源。比对结果显示：激光雷达计算误差和比对误差一致性较好。上述分析结果对于提高激光雷达在气象预报中的应用起到很好的辅助作用。

Analysis of Error Sources on Water Vapour Observed by Raman Lidar

Water vapour has a closely effect on human being. When detecting water vapour, the traditional tools have low spatio-temporal resolution. Lidar can improve the credibility of weather forecast. According to the theory of error analysis, the error sources of water vapour and their contributions are studied form the experimental data. Meanwhile, the computed relative errors are compared with that calculated relative errors from Raman lidar and radiosonde data. It turns out that the error sources on water vapour observed by Raman lidar includes the calibration constant, the transmission correction and the Raman scattering signals. The calibration constant error is about 4% and constant with height, and it is the major contribution to the total error under 1.5 km height. The transmission correction error increases slowly along with the height and less than 4% in the condition of clean air. The Raman scattering signals error is less than 20% under 3 km height, but it becomes the main source above 3 km height. The comparison shows that the relative error derived by Raman Lidar agrees well with the calculated relative error. In summary, the analysis results above are helpful to promote the application of Raman lidar in weather forecast.