差分吸收光谱断层扫描技术重构大气痕量气体空间分布方法及其应用研究

Reconstruction temporal and spatial distributions of atmospheric trace gases are affected by complex meteorology, topography and atmospheric chemistry. As monitoring method is now difficult to meet the demand, it is urgent to develop a new method to monitor trace gas and give its visualization of spatial distribution in a large scale. This project aims to develop a new method to real time monitoring spatial distributions of trace constituents basing on differential optical absorption spectroscopy (DOAS), combining computed tomography(CT). The differential absorption spectrometry tomography gets absorption of atmospheric trace gases in UV and visible band accurately. The beam ray geometry configuration and line integral concentrations for projection are used to reconstruct space distributions of atmospheric trace gas. Reconstruction algorithm will be developed, and guidelines and errors of reconstruction will be given. Visual distributions of trace gases will be obtained. Finally, remote sensing system and reconstruction method will be applied to monitor the daily emission of atmospheric trace constituents and gas plume shape and spatial-temporal change, such as highway and industrial chimneys. The research results not only can provide raw data support for modified atmospheric chemical transport model, search locate sources, estimate total emissions, and study on diffusion, transport, and deposition of atmospheric trace gases, but also can further contribute to the development of optical remote sensing technology. Therefore, this technology will play a much more important role in many fields.

大气痕量成分时空分布的获取受到复杂的气象、地形和化学特性等因素影响，目前的监测模式难以满足需求，亟待一种大范围对其空间分布监测与可视化的新方法。本项目拟以差分吸收光谱法为基础，结合计算机断层扫描技术，提出一种实时监测大气痕量成分空间分布的新方法：通过构建差分吸收光谱断层扫描系统，精确获取大气痕量气体在紫外、可见波段特征差分吸收光谱；在扇形光束射线几何模式下，以精确反演的线积分浓度为投影向量，开发适合大气痕量成分空间分布的重构算法，形成可视化的大气痕量气体空间分布图；并评估重构质量和进行误差分析。最终把遥测系统和重构方法应用于大气痕量成分日常排放实时监测，以及公路和工业烟囱等需要监测气体烟羽形状和时空变化的领域，分析其扩散、传输和沉降过程，为修正大气化学传输模型提供原始数据支持。项目的研究还将有助于光学遥感技术的进一步发展，使该技术在更广阔领域发挥更加重要的作用。

大气痕量成分时空分布的获取受到复杂的气象、地形和化学特性等因素影响，亟待一种大范围对其空间分布监测与可视化的新方法。项目以差分吸收光谱法为基础，结合断层扫描技术，实现了大气痕量气体空间分布的重构。.（1）DOAS断层扫描系统的设计与集成。在DOAS系统的基础上，设计交叉扇形光束几何光路和控制电路，构建DOAS断层扫描系统，实现对大气痕量气体空间分布重构系统集成。（2）大气痕量气体线积分浓度反演算法。利用DOAS断层扫描系统获得扫描光谱，精确获取大气痕量气体在紫外、可见波段特征差分吸收光谱。识别大气痕量气体的特征差分吸收，校正重叠，合理有效地去除干扰成分的影响，并充分考虑各类大气干扰（杂散光和背景辐射等）和仪器参数对测量光谱影响，精确解析大气痕量气体线积分浓度。（3）大气痕量气体空间分布重构算法。建立离散状态模型，对重构算法，进行数值模拟。以精确反演的线积分浓度为投影向量，实现由大气痕量成分的线积分浓度到空间点分布的重构。（4）外场实验。利用该系统在淮北一个燃煤电厂进行外场实验，重构了电厂排放污染气体烟羽空间分布图。. DOAS断层扫描系统应放置在烟羽的下风向处，两台扫描多轴DOAS仪器位于烟囱两边，选择相对稳定的气象条件下，对烟羽的同一垂直断面扫描。该研究为修正大气化学传输模型提供原始数据支持。项目的研究还将有助于光学遥感技术的进一步发展，使该技术在更广阔领域发挥更加重要的作用。