Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution/School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang 330013, China.
Yale-NUIST Center on Atmospheric Environment, International Joint Laboratory on Climate and Environment Change (ILCEC), Nanjing University of Information Science & Technology, Nanjing 210044, China.
Sci Total Environ. 2020 Feb 20;704:135329. doi: 10.1016/j.scitotenv.2019.135329. Epub 2019 Nov 22.
Vertical profiles of PM (i.e., particulate matter with an aerodynamic diameter of 2.5 µm or less) and meteorological variables (e.g., potential temperature, specific humidity) are crucial to understand formation mechanism including accumulation and dispersion process of PM, as well as interactions between aerosols and the atmospheric boundary layer (ABL). In this study, vertical distributions of PM are characterized through comprehensive analyses of vertical profiles measured by unmanned aerial vehicle (UAV), Micro Pulse LiDAR, and other surface observational data of a heavy aerosol pollution episode occurring on December 22-25, 2017 in Nanjing, China. Results show that PM profiles are characterized by a clear three-layer structure with near constant within the mixed layer, a transition layer with a large local gradient in the entrainment zone, and a layer with low concentration and small gradient in the free atmosphere, which shows a large similarity to that of specific humidity. The accumulation of aerosols is found near top of the ABL with the largest increase rate. Vertical distributions of PM and their evolution are largely constrained by the ABL thermodynamics during daytime, but show much less dependence on the ABL evolution at nighttime. PM provides an important feedback on the nocturnal boundary layer (NBL) leading to significant modification of vertical distributions of potential temperature and water vapor. Moreover, this study suggests that the current boundary layer parameterization scheme needs refinement with aerosol radiative effect included to further improve the ABL height (ABLH) and air quality predictions.
PM（即空气动力学直径为 2.5 µm 或以下的颗粒物）和气象变量（如位温、比湿）的垂直廓线对于理解 PM 的形成机制至关重要，包括积累和扩散过程，以及气溶胶与大气边界层（ABL）之间的相互作用。在这项研究中，通过对无人机（UAV）、微脉冲激光雷达和其他表面观测数据进行综合分析，对 2017 年 12 月 22 日至 25 日在中国南京发生的一次严重气溶胶污染事件中的 PM 垂直分布进行了特征描述。结果表明，PM 廓线具有明显的三层结构，混合层内的浓度几乎保持不变，在卷入区有一个大的局部梯度的过渡层，以及在自由大气中浓度低、梯度小的层，这与比湿的特征非常相似。气溶胶的积累发生在 ABL 的顶部附近，增长率最大。白天，PM 的垂直分布及其演化主要受到 ABL 热力学的限制，但夜间对 ABL 演化的依赖较小。PM 对夜间边界层（NBL）产生重要反馈，导致位温和水汽的垂直分布发生显著变化。此外，本研究表明，目前的边界层参数化方案需要改进，包括气溶胶辐射效应，以进一步提高 ABL 高度（ABLH）和空气质量预测。
