基于双视场激光雷达的气溶胶水平分布观测

在自主研制的便携式双视场米散射气溶胶激光雷达（DFOV激光雷达）基础上，探索双视场激光雷达信号拼接思路，利用“斜率-Fernald”方法反演了气溶胶水平消光系数，进而获取了DFOV激光雷达对气溶胶水平消光系数的扫描分布。首先，对雷达回波信号分段运用斜率法，求解最优的气溶胶消光系数、后向散射系数以及相对应的参考距离，然后将该参考点处的后向散射系数代入“Fernald方法”的前后向积分解中，进而得到整条廓线的消光系数。该方法有效避免了“斜率法”中大气均匀的前提假设和消光系数负值的问题，也有效避免了“Fernald方法”对参考点的限制和要求。在获取水平消光系数后，通过拟合近地面空气质量监测点位过顶时刻DFOV激光雷达测量的气溶胶消光系数与PM₁₀质量浓度ρ(PM₁₀)之间的关系，相关性达到0.91。将此定量关系传递至激光雷达扫描的消光系数结果中，可得到气溶胶质量浓度的水平分布，定量反演大气中颗粒物的分布，用于研究近地面大气污染成因、机理和污染来源分析，为DFOV激光雷达进一步应用于城市区域大气污染定量评价和区域空气质量三维模式同化分析研究提供定量的数据支撑。

Mapping for Horizontal Aerosol Density Field by a Portable Dual-FOV Lidar

The three-dimensional (3D) distribution of aerosol was realized based on a home-made dual field of views (DFOV) Mie lidar system. The effective combination method of backscattering signals from the two telescopes was explored to retrieval the aerosol mapping. To implement the lidar mapping of the near-surface aerosol density distribution, a combination of the widely adopted and well-elaborated method of Fernald and the slope method was used. In this combination, the slope method was applied to determine the aerosol extinction and backscattering coefficients in appropriate parts of the lidar beam path. Subsequently, the values of backscattering coefficients of aerosol obtained here were used in retrieving the whole range profiles of extinction coefficients by means of forward- and backward-integrations in the Fernald solutions. As a result, the lidar range profiles of the aerosol extinction coefficients were retrieved with relatively high precision and reliability. In this manner, the advantages of these two approaches are synergistically combined with avoiding priori assumption of atmospheric condition and the reference point, respectively. Then an ideal quantity relationship between the particulate matter mass concentration (ρ(PM₁₀)) and aerosol extinction coefficients was given through a nonlinear fitting with ρ(PM₁₀) monitored by an air quality station (AQS) and the overhead extinction coefficient scanning by DFOV lidar. The fitting Pearson Coefficient was 0.91. The mass concentration density field of aerosol was mapped continuously and online through applying the fitting formula. This quantity study established a foundation for the city-cluster’s air pollution evaluation and the regional 3D air quality model assimilation.