大气边界层内污染物通量扫描激光雷达探测方法与实验研究

Pollutant flux, as one significant physical parameter of atmospheric pollutant transmission intension, it plays an important role in pollution weather forecast and atmospheric condition estimation. Based on Taylor ‘frozen’ hypothesis, a new accuracy detection method for pollutant within atmospheric boundary layer (ABL) using detection mode of scanning lidar with vertical section scanning combined with wind speed and direction tracing function has been proposed. The research is focused on the scanning lidar detection model construction method for pollutant flux, application scope, constrain condition and validation theory of Taylor ‘frozen’ hypothesis, and identification method of scanning lidar multi data fusion algorithm and uncertainties of the retrieval results as well as wind speed and direction tracing, and the ultimate goal is to establish a new theory and method for pollutant flux accuracy detection using scanning lidar. The achievement of this research is not only to provide brand new solution for pollutant flux, but also through validation of the application scope of Taylor ‘frozen’ hypothesis to realize the substitution detection of one point within space to several points within space along average wind direction so as to solve restriction problem of remote sensing detection for complex construction of city local underlying surface, to make further study of pollutant transmission mechanism in order to improve pollution weather situation as well as to provide reliable theoretical and technical analysis for extension application of lidar.

污染物通量是表征大气污染物输送强度的重要物理参量，在评估大气环境状况以及污染天气预报中具有重要的作用。项目提出基于泰勒“冻结”假设的激光雷达垂直剖面扫描与风速风向探测相结合的边界层内污染物通量的精细探测新方法。重点研究污染物通量的扫描激光雷达探测模型的构建方法、泰勒“冻结”假设的适用范围与约束条件的验证方法、风速风向自动追踪和扫描激光雷达多数据融合算法及探测结果不确定性的辨识方法，以期构建扫描激光雷达精细探测污染物通量的新理论和新方法。项目的研究成果不仅为污染物通量探测提供全新的解决方案，而且通过验证泰勒“冻结”假设的适用条件，可实现利用空间上一固定点的观测结果替代同时段沿平均风方向空间各点的观测结果的激光雷达应用方案，解决城市局地探测下垫面复杂结构对激光遥感探测污染物通量的制约问题，为研究污染物的输送机理，改善污染天气状况以及扩展激光雷达的应用提供可靠的理论和技术支持。

针对目前污染物通量主要依赖于模式计算没有直接探测手段的问题，本项目紧密围绕基于扫描米散射激光雷达结合多普勒测风激光雷达探测污染物通量的实验方法展开研究，升级了现有的扫描米散射激光雷达，实现了与多普勒测风激光雷达同步观测及数据匹配融合，构建了扫描激光雷达与测风激光雷达数据结合的污染物通量探测模型，推演了固定扫描模式下的污染物通量的反演公式并开展了同步观测实验，获得了西安地区观的污染物通量的初步探测结果。统计分析了全年的风速风向规律，并根据大气边界层结构特征，采用分层、分块的数据处理手段对通量按照高度层进行空间尺度的数据分析，在除去极端天气条件下，风场信息存在明显的空间分层特性和时间分布特性。提出了利用扫描激光雷达结合测风激光雷达验证泰勒冻结假设的实验验证方法，对在主导风向平稳的条件下的泰勒冻结条件进行了验证，建立了适用条件数据库。实验过程中，积累了大量的边界层内气溶胶时空分布数据和风场数据，该数据还可用于气溶胶演变规律，边界层高度变化，气溶胶对气候的影响，沣渭平原雾霾的形成与扩散机理，风力资源有效利用，飞行器的运动安全等方面的研究。污染物通量的探测结果对于了解大气污染物的理化特性、空间分布、输送机制有重要的理论意义，而且在气候的研究，大气环境的治理，城镇规划和工业布局等方面有应用前景和指导意义。