Key Laboratory of Beijing on Regional Air Pollution Control, Beijing University of Technology, Beijing 100124, China.
Key Laboratory of Beijing on Regional Air Pollution Control, Beijing University of Technology, Beijing 100124, China.
J Environ Sci (China). 2023 Mar;125:831-842. doi: 10.1016/j.jes.2021.11.018. Epub 2022 May 11.
This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertical exchanges and further discusses the impact of the atmospheric boundary layer (ABL)-free troposphere (FT) exchange on concentration of fine particulate matter (PM) within the ABL during heavy pollution. From the perspective of the transport flux balance relationship, differences in pollution transport characteristics between the two cities is mainly reflected in the ABL-FT exchange effect. The FT mainly flowed into the ABL in BJ, while in SJZ, the outflow from the ABL to the FT was more intense. Combined with an analysis of vertical wind profile distribution, BJ was found to be more susceptible to the influence of northwest cold high prevailing in winter, while sinking of strong cold air allowed the FT flowing into the ABL influence the vertical exchange over BJ. In addition, we selected a typical pollution event for targeted analysis to understand mechanistic details of the influence of ABL-FT exchange on the pollution event. These results showed that ABL-FT interaction played an important role in PM concentration within the ABL during heavy pollution. Especially in the early stage of heavy pollution, FT transport contributed as much as 82.74% of PM within the ABL. These findings are significant for improving our understanding of pollution transport characteristics within the boundary layer and the effect of ABL-FT exchange on air quality.
本研究从水平和垂直交换的角度首次对京津冀地区典型城市边界层内的污染传输收支进行了定量评估，并进一步讨论了大气边界层（ABL）-自由对流层（FT）交换对重污染期间边界层内细颗粒物（PM）浓度的影响。从传输通量平衡关系的角度来看，两个城市的污染传输特征差异主要反映在 ABL-FT 交换效应上。FT 主要流入 BJ 的 ABL，而在 SJZ，ABL 向 FT 的流出更为强烈。结合垂直风廓线分布的分析，发现 BJ 更容易受到冬季西北寒冷高压的影响，而强烈冷空气的下沉则允许 FT 流入 ABL 影响 BJ 的垂直交换。此外，我们选择了一个典型的污染事件进行针对性分析，以了解 ABL-FT 交换对污染事件的影响的机制细节。这些结果表明，ABL-FT 相互作用在重污染期间的边界层内 PM 浓度中起着重要作用。特别是在重污染的早期阶段，FT 输送对边界层内 PM 的贡献高达 82.74%。这些发现对于提高我们对边界层内污染传输特征以及 ABL-FT 交换对空气质量影响的认识具有重要意义。
