Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing 210023, China.
Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing 210023, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, China.
Sci Total Environ. 2021 May 10;768:144520. doi: 10.1016/j.scitotenv.2020.144520. Epub 2021 Jan 7.
Tropospheric ozone (O) can be transported influenced by large-scale circulation. In this study, an ozone pollution episode in 6 cities of southeastern coastal area of China (SCA) in autumn 2017 was investigated. Compared with the typical local ozone pollution, there was no significant diurnal variations in this pollution episode, the O concentrations maintained a stable level of about 47 ppb continuously. The WRF-CMAQ model as well as the coupled process analysis (PA) and source apportionment modules were used to simulate the formation and transport and quantify the contributions to O. Besides, the HYSPLIT model was used to calculate the backward trajectories arriving in the cities. We find that this pollution was mainly caused by O transport from the eastern China seas (ECS). Under the movement of the Mongolian high-pressure, the O precursors emitted from Beijing-Tianjin-Hebei (BTH), Northeast China (NEC) and Japan-Korea (JK) were transported to ECS then generated O through photochemical reactions. Due to the weak nitrogen oxide titration and the extremely weak ozone deposition on the water surface, O concentrations maintained high during the movement of air masses over ECS and finally affected SCA after long-range transport. The contributions of horizontal advections were significant basically all the day with hourly contribution about 10 ppb hr and extended from surface to 500 m above the ground level. JK contributed the most, with multi-days averaged contribution about 5 ppb and peak up to 30 ppb. The contributions of BTH and NEC were comparable, with average about 2 ppb and hourly peak of 19 and 10 ppb, respectively. For the first time, this study clearly shows that the O precursors emitted from northern China and Japan-Korea contribute to the O pollution in SCA under certain weather conditions, which will help to better understand and predict the O pollution in that area.
对流层臭氧 (O) 可受大规模环流的影响进行传输。本研究调查了 2017 年秋季中国东南沿海 6 个城市的一次臭氧污染事件。与典型的局地臭氧污染相比，此次污染过程中没有明显的日变化，O 浓度连续稳定在约 47 ppb。使用 WRF-CMAQ 模型以及耦合过程分析 (PA) 和源分配模块来模拟形成和传输过程，并量化 O 的贡献。此外，还使用 HYSPLIT 模型计算到达城市的后向轨迹。我们发现，此次污染主要是由来自东海的 O 传输引起的。在蒙古高压的作用下，京津冀、东北和日韩排放的 O 前体物质被输送到东海，然后通过光化学反应生成 O。由于氮氧化物滴定作用较弱，以及臭氧在水面上的沉积作用极弱，在大气团经过东海的过程中，O 浓度保持在较高水平，最终在长距离传输后影响到东南沿海地区。水平平流的贡献基本全天都很显著，每小时贡献约 10 ppb，从地面延伸到 500 米高空。日本贡献最大，多日平均贡献约 5 ppb，峰值可达 30 ppb。京津冀和东北的贡献相当，平均约为 2 ppb，峰值分别为 19 和 10 ppb。本研究首次清楚地表明，在一定天气条件下，来自中国北方和日本-韩国的 O 前体物质对东南沿海地区的 O 污染有贡献，这将有助于更好地理解和预测该地区的 O 污染。
