大气能见度是重要的气象参数，实时准确地获取其信息对于交通运输保障、环境监测预报等具有重要意义。传统的单波长米散射激光雷达测量方法在反演过程中需对雷达比和边界值作假设或近似处理，制约了反演结果的精度。本项目基于拉曼激光雷达反演无需假设雷达比和边界值的特点，提出利用米-拉曼散射激光雷达联合精确测量能见度的方法，主要研究内容包括：基于米散射激光雷达，研究激光器波长扩展、多通道信号采集等技术，构建联合探测平台；利用变分模态分解法实现高效地自适应信号去噪，提高回波信号信噪比；基于多路米散射和拉曼回波信号，采用Ansmann法获取准确的雷达比；依据拉曼和米散射消光系数反演结果的相关性精确修正边界值，提高米散射通道消光系数廓线的反演精度；在此基础上，以透射仪测量结果为标准，建立二系数修正模型，实现能见度的精确修正和标定。该方法不仅能提高米散射激光雷达的反演精度，而且可突破拉曼激光雷达探测距离受限的瓶颈。

Atmospheric visibility is an important meteorological parameter. It is of great significance to obtain its information in real time and accurately for transportation support and environmental monitoring and forecasting. The traditional single wavelength Mie scattering lidar measurement method needs to assume or approximate the lidar ratio and the boundary value in the inversion process, which restricts the accuracy of the inversion result. Based on the characteristics of inversion of extinction coefficient without assuming the lidar ratio and the boundary value for Raman lidar, this project proposes a method of accurate measurement of visibility by using Mie-Raman scattering lidar. The main research contents include: First, based on the Mie scattering lidar, the technology of laser wavelength expansion and multi-channel signals acquisition are studied, and a joint Mie-Raman detection platform is constructed. Then, high efficiency adaptive signal denoising is realized by applying the variational mode decomposition (VMD) algorithm to improve signal to noise ratio of the echo signal. Third, the Ansmann method is used to obtain accurate lidar ratio based on multi-channel Mie scattering and Raman echo signals. Next, accurate correction of the boundary value is performed based on the correlation between the extinction coefficient profiles obtained by the Raman and the Mie scattering lidar, and then the inversion accuracy of the Mie scattering lidar is improved. On this basis, the two-coefficient correction model is set up to achieve accurate correction and calibration of visibility with the measurement result of the transmission visibility meter as the standard. This method can not only improve the inversion accuracy of the Mie scattering lidar, but also break through the bottleneck of the detection distance limitation of Raman lidar.