Institute for Environmental and Climate Research, Jinan University, Guangzhou, 510632, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China.
Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031, China.
Environ Pollut. 2021 Jan 1;268(Pt A):115804. doi: 10.1016/j.envpol.2020.115804. Epub 2020 Oct 10.
Vertical measurements of ozone (O) within the 3000-m lower troposphere were obtained using an O lidar to investigate the contribution of the interactions between the transport and boundary layer processes to the surface O levels in urban Shanghai, China during July 23-28, 2017. An extremely severe pollution episode with a maximum hourly O mixing ratio of 160.4 ppb was observed. In addition to enhanced local photochemical production, both downward and advection transport in the lower troposphere may have played important roles in forming the pollution episode. The O-rich air masses in the lower free troposphere primarily originated from central China and the northern Yangtze River Delta (YRD) region. The downward transport of O from the lower free troposphere may have an average contribution of up to 49.1% to the daytime (09:00-16:00 local time) surface O in urban Shanghai during the pollution episode (July 23-26, 2017). As for the advection transport, large amounts of O were transported outward from Shanghai in the planetary boundary layer under the influence of southeasterly winds during the field study. In this condition, the boundary-layer O that was transported downward from the free troposphere in Shanghai could be transported back to the northern YRD region and accumulated therein, leading to the occurrence of severe O pollution events over the whole YRD region. Our results indicate that effective regional emission control measures are urgently required to mitigate O pollution in the YRD region.
利用臭氧激光雷达对 3000 米以下对流层中的臭氧进行了垂直测量，以研究传输和边界层过程之间的相互作用对中国上海城区地面臭氧水平的贡献，观测时间为 2017 年 7 月 23 日至 28 日。观测到了一次极端严重的污染事件，最大小时臭氧混合比达到 160.4 ppb。除了增强的局地光化学反应生成之外，对流层低层的向下和平流输送可能在此次污染事件的形成中起了重要作用。对流层自由低层富含臭氧的空气团主要来源于中国中部和长江三角洲北部地区。臭氧从自由对流层向下输送可能对污染事件期间（2017 年 7 月 23 日至 26 日）上海城区白天（09:00-16:00 地方时）的地面臭氧有平均高达 49.1%的贡献。对于平流输送，在东南风的影响下，大量臭氧在边界层中从上海向外输送。在这种情况下，从上海自由对流层向下输送的边界层臭氧可能会被输送回北部长江三角洲地区并在那里积累，导致整个长江三角洲地区发生严重的臭氧污染事件。研究结果表明，长江三角洲地区迫切需要采取有效的区域排放控制措施来减轻臭氧污染。
