气溶胶光学特性测量是气溶胶辐射效应研究的重要基础。目前的观测研究主要集中在地面气溶胶光学性质的直接测量和整层大气气溶胶光学性质的遥感反演。气溶胶光学特性的垂直分布极大地影响着气溶胶辐射效应评估的可靠性和准确性，但相关的观测研究尤其是原位观测却相当有限。.本项目计划在华北地区开展气溶胶光学特性垂直分布的飞机观测。特别的，基于多角度散射系数等的原位测量发展散射相函数的反演算法，并应用于飞机观测首次获得其垂直廓线。通过大量飞行试验，比较系统地研究这一地区气溶胶光学特性（吸收系数、散射系数、消光系数、单次散射反照率、不对称因子、散射相函数等）的垂直分布特征，并根据观测用辐射传输模式计算气溶胶的辐射效应。气溶胶光学特性垂直分布的观测研究，特别是散射相函数的观测研究，将为准确评估气溶胶的直接辐射强迫提供宝贵的观测资料，相关研究结果还具有地基和空基遥感以及辐射传输计算方面的应用价值。

Measurements of aerosol optical properties form a critical foundation for investigating aerosol radiative effects. Current observational studies focus mainly on ground-based measurements of aerosol optical properties and the remote sensing of columnar aerosol optical properties. Vertical distributions of aerosol optical properties largely influence the reliability and accuracy of the estimation of aerosol radiative effects. However, observational studies regarding vertical profiles of aerosol optical properties especially in-situ measurements are still quite limited. This project intends to carry out aircraft measurements of vertical distributions of aerosol optical properties in the North China Plain (NCP). Particularly, vertical distributions of scattering phase function will for the first time be obtained from aircraft measurements by utilizing an inversion algorithm, which is developed on the basis of measured aerosol optical properties including multi-angle scattering coefficients. Vertical profiles of aerosol optical properties (such as absorption coefficients, scattering coefficients, extinction coefficients, single scattering albedo, asymmetry factor, scattering phase function) will be synthetically investigated through intensive flight experiments. The impact of aerosols on radiation will be estimated by observation-based radiative transfer model simulations. Observational studies on vertical distributions of aerosol optical properties, especially those on scattering phase function, will provide valuable data for accurately estimating aerosol direct radiative forcing. Corresponding results also have important application for data retrieval in satellite- and ground-based remote sensing and the radiative transfer modeling.