基于被动差分吸收光谱仪观测的O4吸收研究气溶胶光学特性

Aerosol plays an important role in atmosphere radiation and climate change research, and its optical property is a precondition for the estimation of the forcing of aerosol on radiation. A new method for detecting the aerosol on a large scale is urgently needed. In the project, combined with 2-dimensional and multiple-axis techniques, a new method of real-time online monitoring for aerosol optical properties (aerosol optical depth, asymmetry factor, single scattering albedo) based on Differential Optical Absorption Spectroscopy (DOAS) is studied. O4 is essentially constant and its absorption depends on the photon transmission path and atmospheric scattering processes. Combining the measurements and the radiative transfer simulations, the sensitivity study of O4 absorption on aerosol optical properties under different atmospheric conditions and observation geometry is carried out. The key retrieval parameter and measurement method is studied to obtain aerosol optical properties by using the O4 absorption. As a result, the rapid, stable inversion method based on multi-dimensional look-up table is established and a 2-dimensional ground-based system for acquiring the spectrum in different directions is set up. The remote measuring system and retrieval method are applied to constantly detect the aerosol optical properties and analyze its radiation force mechanism. The research result offers more accurate data for estimating the aerosol radiative forcing effect, and input parameters for the atmospheric pattern research.

气溶胶在大气辐射和气候变化研究中具有重要作用，其中气溶胶光学特性的获取已成为准确估算其辐射强迫的前提条件，亟需一种大范围对其监测的新方法。本项目拟以差分吸收光谱技术（DOAS）为基础，结合二维多轴技术，开展实时、在线获取气溶胶光学参量（气溶胶光学厚度、非对称因子、单次散射反照率）的新方法研究。O4气体在大气中分布基本不变，观测到的O4吸收依赖于光子传输路径和大气散射。通过观测和模型相结合，研究O4吸收在不同大气条件和观测方式下对气溶胶光学参量的灵敏度，确定反演关键参数和最佳测量方式，建立基于参数化查表方法的快速稳定反演算法，搭建能实现全天空不同角度测量的地基二维多轴DOAS系统，最终把遥测系统和反演方法应用于气溶胶光学特性实时监测中，研究地区的气溶胶光学特性，分析其辐射强迫机制。项目研究成果可为估算气溶胶辐射强迫提供更准确的数据支撑，并为大气模式研究提供了更准确的输入参数。

气溶胶在大气辐射和气候变化中具有重要作用，其中气溶胶光学特性的获取已成为准确估算其辐射强迫的前提条件，而光学参数的准确获取是气溶胶探测技术中的重要问题。被动差分吸收光谱技术主要用于大气痕量气体和气溶胶柱浓度及廓线获取，但对非对称因子、单次散射反照率等光学参数研究较少。. 本项目利用地基MAX-DOAS观测的O4吸收开展了气溶胶光学特性的测量研究。（1）研究了基于O4吸收的气溶胶光学参数反演问题，采用大气辐射传输模型McArtim分析O4吸收相对于气溶胶光学参数的敏感性，通过敏感性分析结果确定了反演关键参数和最佳测量方法。建立了基于参量化查表方法的反演算法，通过查找表和测量值相结合获得代价函数，结合模型和迭代优化获取准确的气溶胶光学参数。（2）构建了针对O4测量的地基二维MAX-DOAS系统，对测量仰角和方位角进行精确控制和跟踪，实现全天空不同角度光谱的准确获取。（3）开展了外场实验和对比分析，获得气溶胶光学参量并与其他仪器观测结果进行对比，评估结果并进一步改进算法。该研究为探索气溶胶光学参量测量方法和分析气溶胶在环境和气候变化方面作用提供科学依据。该项目的研究还将推动DOAS技术的进一步发展和应用。