School of Atmospheric Sciences, Nanjing University, Nanjing, 210023, China.
School of Atmospheric Sciences, Nanjing University, Nanjing, 210023, China.
Environ Pollut. 2020 Feb;257:113631. doi: 10.1016/j.envpol.2019.113631. Epub 2019 Nov 16.
Severe ozone (O) pollution in China has magnified global concerns over the past years. Exploring the synoptic impacts and quantifying the source contributions are important for mitigating O pollution. This study focuses on the summertime O pollution over the Yangtze River Delta (YRD) in eastern China. We identify six predominant synoptic weather patterns (SWPs) over the YRD during 2013-2017 using the self-organising map (SOM) approach. We conduct O source attribution based on ozone source apportionment technology (OSAT) in a regional transport model. Surface O pollution is found to be sensitive to the predominant SWPs, including four O-polluted types (northeasterly, northerly and southwesterly and anticyclone) and two O-clean types (cyclone and the Meiyu front). The integrated influences of local chemistry and regional transport are important in O pollution under different SWPs. Daily maximum 8-h average (MDA8) O holds strong negative and positive correlations with relative humidity and sunshine duration, respectively. Among the six SWPs, the concentration and exceedance of MDA8 O reach their maxima under the northerly type on a regional average. Higher O levels, particularly under the northerly and northeasterly types, are primarily related to regional transport on various spatial scales. Local production accounts for the largest proportion of O sources under the anticyclone type. Under the southwesterly type, favourable weather conditions superimposed on regional transport lead to severe O pollution in coastal cities. The impact of super-regional transport is most pronounced along the eastern coast under the cyclone type. Source category analysis shows that transportation and industrial emissions play a prime role in surface O formation. This study illustrates the imperative implementation of joint emission control over eastern China to reduce O pollution.
近年来，中国严重的臭氧（O）污染引起了全球的关注。探索天气形势的综合影响并量化污染源的贡献对于减轻 O 污染至关重要。本研究聚焦于中国东部长江三角洲（YRD）地区的夏季 O 污染。我们使用自组织映射（SOM）方法，确定了 2013 年至 2017 年期间 YRD 地区的六种主要天气形势（SWPs）。我们在区域传输模型中基于臭氧源解析技术（OSAT）进行 O 源归因。结果表明，地面 O 污染对主要 SWPs 非常敏感，包括四种 O 污染类型（东北风、北风和西南风以及反气旋）和两种 O 清洁类型（气旋和梅雨锋）。在不同的 SWPs 下，局地化学和区域传输的综合影响对 O 污染很重要。日最大 8 小时平均（MDA8）O 浓度与相对湿度和日照时间呈强负相关和正相关。在六种 SWPs 中，平均而言，在北风类型下，MDA8 O 的浓度和超标率达到最大值。在较高的 O 水平下，特别是在北风和东北风类型下，与各种空间尺度的区域传输密切相关。在反气旋类型下，局地生产对 O 源的贡献最大。在西南风类型下，有利的天气条件叠加在区域传输上，导致沿海城市出现严重的 O 污染。在气旋类型下，沿东部海岸的超区域传输的影响最为显著。源类别分析表明，交通运输和工业排放对地表 O 形成起着重要作用。本研究说明了在中国东部实施联合排放控制以减少 O 污染的必要性。
