PM2.5浓度时空分布的激光雷达精细探测研究

PM2.5 is harmful to human health and environment, and it is an important parameter reflecting the air quality. There is a certain correlation between the PM2.5 concentration and the extinction coefficient obtained by lidar detection. Due to the lack of near range signals, it is difficult to get the correct extinction coefficient by lidar in the near range, which limits the detection of PM2.5 concentration by lidar. In the previous study it was found that the atmospheric extinction coefficient corrected by calculated overlap factor was consistent with the actual weather condition. This project is to study the temporal and spatial distribution of PM2.5 concentration using lidar. A fine quantitative relationship model of PM2.5 concentration and aerosol extinction coefficient by lidar will be established and corrected by meteorological factors. PM2.5 concentration profiles are expected to be retrieved from lidar data using the established model. The temporal and spatial distribution of PM2.5 concentration will be studied through long-term continuous detection. The project will provide theoretical basis and data support for air pollution research and prevention.

PM2.5是气溶胶中对人类健康和环境的危害较大的一类，是反映空气质量的重要参数。PM2.5浓度与激光雷达探测获得的消光系数之间有一定的相关性。现有激光雷达因为存在近场信息缺失问题，较难获得正确的近地面消光系数，从而限制了激光雷达对PM2.5浓度的探测。申请人前期研究发现，利用理论计算的离轴激光雷达重叠因子对近场信号校正，可以获得更符合真实大气状况的气溶胶近场信息。本项目拟利用激光雷达研究PM2.5浓度时空分布规律，建立PM2.5浓度和激光雷达探测的气溶胶消光系数的精细定量关系模型，并充分考虑气象因素的影响，对模型加以修正。利用建立的模型从激光雷达探测数据反演PM2.5浓度廓线，通过长期连续探测研究PM2.5浓度时空分布规律，为大气污染的研究及防治提供理论依据及数据支撑。

近地面气溶胶中的PM2.5是反映空气质量的重要参数，与激光雷达探测获得的消光系数之间有一定的相关性。但在实际探测中，由于激光雷达系统存在近场信号缺失的问题，较难获得正确的近地面消光系数，这直接限制了激光雷达在近地面大气研究中的应用。本项目对大气探测中广泛使用的离轴激光雷达系统的近场信号缺失问题进行了研究，考虑到收发光轴不平行的情况，推导出了重叠因子解析式，并模拟了其对不同参数的依赖关系。根据实验所用激光雷达系统参数的实测数据，对探测到的回波信号进行校正，反演得到了近地面消系数的真实值，讨论了近地面消光系数和PM2.5浓度的对应关系，分析了不同高度气溶胶粒子的来源。研究了极端天气下的PM2.5和TSP之间的相关性及PM2.5/PM10的比值变化。研究了利用激光雷达探测结果获取大气边界层特征参数的方法。本项目研究成果对大气激光雷达信号反演及实际应用、监测和改善本地区的大气环境现状、大气科学研究和气象预报有十分重要的意义，所得结果亦可用于气象部门的数据分析，为大气污染的研究及防治提供理论依据及数据支撑。