Interaction influence characteristics of air quality and aerosol properties between Beijing-Tianjing-Hebei (BTH) and Yangtze River Delta (YRD), China

In the past decade, frequent large-scale regional pollution events have occurred in the key economic and population centers of eastern China, including Beijing-Tianjin-Hebei (BTH) and the Yangtze River Delta (YRD). Although local emissions are important contributors, the transport processes and driving mechanisms of these events are still poorly understood. This study comprehensively analyzes long-term air quality, aerosol properties, and meteorological conditions in the BTH and YRD regions, as well as the Shandong-Henan (SDHN) transitional area between these two urban clusters, from March 2015 to February 2021. Additionally, it examines the processes of pollutant transport and evolution during extreme pollution events. The results indicate an annual improvement in air quality in the study area. The monsoon influences aerosol composition and distribution, with dust carried in winter and sea salt predominating in summer. High-pressure systems often herald the onset of regional pollution outbreaks, with their location and wind direction determining pollutant propagation pathways. Meanwhile, the southward movement of strong cold air from the north plays a crucial role in alleviating large-scale regional pollution by breaking the inversion layer and facilitating rapid pollutant dispersion. This study provides a new perspective for air quality monitoring in the urban clusters of eastern China.