School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, 519082, China; Guangdong Provincial Observation and Research Station for Climate Environment and Air Quality Change in the Pearl River Estuary, Key Laboratory of Tropical Atmosphere-Ocean System, Ministry of Education, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519082, China.
School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, 519082, China; Guangdong Provincial Observation and Research Station for Climate Environment and Air Quality Change in the Pearl River Estuary, Key Laboratory of Tropical Atmosphere-Ocean System, Ministry of Education, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519082, China.
Environ Pollut. 2022 Aug 1;306:119464. doi: 10.1016/j.envpol.2022.119464. Epub 2022 May 12.
In this study, the spatiotemporal variabilities and characteristics of ozone (O) and fine particulate matter (PM) were reconstructed, and the interaction between meteorological conditions and the co-occurrence of O and PM in Zhuhai, a city in the Pearl River Delta (China), was analysed. The vertical distributions of lower tropospheric O, aerosol extinction coefficient, and wind velocity were measured using a ground-based LiDAR system. The diurnal variations in air pollutant concentrations and meteorological conditions at ground level were examined from 28 November to December 8, 2020 considering the weather conditions in Zhuhai. Heavy pollution episodes with increased concentrations of O and PM were observed from 6 to 7 December after a period of cold air invasion. The maximum hourly average concentrations of O and PM at the ground level reached up to 190 μg/m, 98 μg/m, respectively. The horizontal wind speed rapidly decreased to less than 2 m/s during the heavy pollution episodes driven by O and PM, whereas the vertical wind velocity was dominated by the downdraught. When the large-scale synoptic winds were weak, a strengthening sea breeze in the afternoon could promote the landward propagation of warm marine air masses, and a lower surface wind speed was driven by the convergence of cold air from the north and warm air from the south. In turn, this increased the residence time of air pollutants and promoted their conversion to secondary pollutants. Regarding the pollution sources, the results indicated that the Pearl River Estuary represented a 'pool' of O and PM pollution. In addition, the contribution of regional pollutant transport could not be ignored when considering the accumulative increase in air pollution. Overall, the relatively weak synoptic winds, low mixing height, and high generation of pollution around Zhuhai collectively resulted in high concentrations of O and PM.
本研究重建了臭氧（O）和细颗粒物（PM）的时空变化特征，并分析了气象条件与臭氧和 PM 同时出现的相互作用。利用地基激光雷达系统测量了下对流层 O、气溶胶消光系数和风速的垂直分布。考虑到珠海的天气条件，从 2020 年 11 月 28 日至 12 月 8 日，考察了地面空气污染物浓度和气象条件的日变化。在冷空气入侵一段时间后，12 月 6 日至 7 日观察到臭氧和 PM 浓度增加的重度污染事件。地面上臭氧和 PM 的最大小时平均浓度分别高达 190μg/m 和 98μg/m。在重度污染事件中，水平风速迅速下降到 2m/s 以下，而垂直风速主要受下沉气流的控制。当大尺度天气系统较弱时，下午增强的海风可以促进温暖海洋空气团的向岸传播，由于冷空气从北向南的汇聚和暖空气的汇聚，地面风速降低。这反过来又增加了空气污染物的停留时间，并促进了它们向二次污染物的转化。关于污染源，结果表明珠江口是臭氧和 PM 污染的“汇集区”。此外，在考虑空气污染的累积增加时，区域污染物传输的贡献不容忽视。总体而言，珠海周边较弱的天气系统、较低的混合层高度和较高的污染生成导致了高浓度的臭氧和 PM。
