基于拉曼偏振雷达的城市细颗粒物光学-微物理特性研究

Urban fine particles,which lead to the severe air pollution (eg haze ,photochemical smog ), have endangered the social development and caused great harm to the human health.It becomes one of the most urgent environmental problems to be solved in the recent years.And the optical-physical properties of the fine particles are important parameters to analyze the cause of haze and pollution transportation.However at present,although many researches have been focused on the chenmical composition, souce appointment and toxic mechanism ,the fine particles are still lack of comprehensive inversion model for the optical-microphysical properties and its vertical distribution in our country. So to develop an effective remote sensing technology and retrieval model for the urban fine particles have important scientific significance and application value. In this study firstly the optical properties retrieval algorithm based on the Raman-Polarized lidar is improved. Then the microphysical properties retrieval model is investigated together with the data fusion from the sunphotometer . The impact of relative humidity on the soluble particles is discussed to make correction for the model under different particle modes and chemical composition. The scatter-mass concentration conversion factor is also discussed to get the mass concentration vertical distribution according to Mie theory .

城市细颗粒物引起的大气污染(如灰霾、光化学烟雾) 已对我国社会发展和人民生存环境造成严重影响和危害，是亟待解决的首要环境问题之一。城市细颗粒物的光学物理特性是分析大气城市灰霾成因和污染物传输的重要参数。目前国内在细颗粒物化学构成、来源解析及毒性机理方面开展了相关分析，但在城市细颗粒物光学-微物理特性和垂直分布特征方面缺乏综合研究。因此采用有效的探测技术对细颗粒物进行特征参数的遥测研究，具有重要科学意义和应用价值。 本课题主要开展基于激光雷达的城市细颗粒物特性参数测量方法研究，利用双波段拉曼偏振雷达进行米-拉曼信号联合算法反演，获取光学特性参数；开展激光雷达与太阳光度计的协同测量和数据融合研究，建立迭代比对模型，获取微物理特性参数；探索不同气溶胶类型模态和化学构成下，相对湿度对颗粒物的影响，进行模型修正；根据已获参数和Mie理论数值模拟散射-质量浓度转换因子，获取质量浓度时空分布特征。

城市细颗粒物的光学-微物理特性是分析大气城市灰霾成因和污染物传输的重要参数。目前国内缺乏城市细颗粒物光学-微物理特性综合参数的提取模型，因此迫切需要采用有效的探测技术对细颗粒进行特征参数遥测研究。. 本课题以355-532拉曼-偏振激光雷达为主体的观测平台为基础，采集双波长米散射、拉曼散射信号，用拉曼信号来校正米散射信号，提高消光系数反演精确度，准确获取了散射消光比、光学厚度、Angstrom指数等细颗粒物光学特性参数；通过与太阳光度计的协同测量分析，获得了以复折射指数、粒谱分布为主的细颗粒物微物理特征；利用理论计算，开展了相对湿度对水溶性细颗粒物的影响分析，修正了细颗粒物微物理特征反演算法；利用已获取的上述细颗粒物参数特性，利用Mie理论计算单模尺度和多模尺度下的细颗粒物散射——质量浓度转换因子，实现了城市细颗粒物质量浓度时空分布研究观测。结果表明，本算法对近地面及高空中的细颗粒物层更为敏感；当相对湿度小于75%时，质量浓度模型反演准确性提高，但由于季节性，污染源等变化，为了得到较高精度的结果，应定期更新消光系数和PM2.5质量浓度间的拟合公式。