State Key Laboratory of Severe Weather (LASW) and Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, CMA, Beijing 100081, China; Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China.
State Key Laboratory of Severe Weather (LASW) and Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, CMA, Beijing 100081, China.
Sci Total Environ. 2019 Feb 10;650(Pt 2):1846-1857. doi: 10.1016/j.scitotenv.2018.09.262. Epub 2018 Sep 24.
As the central part of eastern China, the Yangtze River Delta (YRD) region, with its rapid economic growth and industrial expansion, has experienced severe air quality issues. In this study, the monthly variation and interaction between aerosol direct radiative forcing (ADRF) and aerosol vertical structure during 2013-2015 over the YRD were investigated using ground-based observations from a Micro Pulse Lidar (MPL) and a CE-318 sun-photometer. Combining satellite products from MODIS and CALIPSO, and reanalysis wind fields, an integrated discussion of a biomass burning episode in Hangzhou during August 2015 was conducted by applying analysis of optical properties, planetary boundary layer (PBL), spatial-temporal and vertical distributions, backward trajectories, Potential Source Contribution Function (PSCF), and Concentration Weighted Trajectory (CWT). The results reveal that a shallower PBL coincides with higher scattering extinction at low altitude, resulting in less heating to the atmosphere and radiative forcing to the surface, which in turn further depresses the PBL. In months with a deeper PBL, the extinction coefficient decreases rapidly with altitude, showing stronger atmospheric heating effects and ADRF to the surface, facilitating the turbulence and vertical diffusion of aerosol particles, which further reduces the extinction and raises the PBL. Because of the hygroscopic growth facilitated by high relative humidity, June stands out for its high scattering extinction coefficient and relatively low PBL, and the reduced ADRF at the surface and the enhanced cooling effect on near-surface layer in turn depresses the PBL. Absorptive aerosols transported from biomass burning events located in Zhejiang, Jiangxi, and Taiwan provinces at 1.5 km, result in high ADRF efficiency for atmospheric heating. And the enhanced heating effect on near-surface layer caused by absorptive particles facilitates PBL development in August over the YRD.
作为中国东部的中心地带，长三角（YRD）地区经济增长迅速，工业扩张迅速，但也经历了严重的空气质量问题。本研究利用地基微脉冲激光雷达（MPL）和 CE-318 太阳光度计的观测数据，结合 MODIS 和 CALIPSO 卫星产品以及再分析风场，研究了 2013-2015 年期间长三角地区气溶胶直接辐射强迫（ADRF）与气溶胶垂直结构的月变化及其相互作用。通过分析光学特性、行星边界层（PBL）、时空和垂直分布、后向轨迹、潜在源贡献函数（PSCF）和浓度加权轨迹（CWT），对 2015 年 8 月杭州发生的生物质燃烧事件进行了综合讨论。结果表明，较浅的 PBL 与低空高散射消光相对应，导致对大气加热和对地表的辐射强迫较小，从而进一步抑制了 PBL。在 PBL 较深的月份，消光系数随高度迅速下降，对大气的加热效应和对地表的 ADRF 更强，促进气溶胶粒子的湍流和垂直扩散，进一步降低消光率并提高 PBL。由于高相对湿度促进的吸湿性增长，6 月表现出较高的散射消光系数和相对较低的 PBL，以及地表 ADRF 的降低和近地表层冷却效应的增强，从而进一步抑制了 PBL。从浙江、江西和台湾省生物质燃烧事件输送到 1.5km 高度的吸收性气溶胶，对大气加热具有较高的 ADRF 效率。而吸收性粒子对近地层的加热增强效应，有利于 8 月长三角地区 PBL 的发展。
