The northward typhoon configuration along the southeast coast of China (TCN-SEC) is one of the key circulation patterns influencing the coastal cities in southeast China (CCSE). Here, we analyzed the air quality in CCSE during the high-incidence typhoon period from 2019 to 2021. Multi-source measurements were carried out to explore the impact of super typhoon 2114 ‘Chanthu’ on the air quality in CCSE. The results showed that the TCN-SEC and its surrounding weather situation had a favorable impact on the increase in pollutant concentration in CCSE, especially on the increase in O3 concentration. From 13 September to 17 September 2021, affected by the cyclonic shear in the south of super typhoon 2114 ‘Chanthu,’ the strong wind near the ground, stable relative humidity, strong precipitation, and the significantly reduced wind speed had a substantial effect on PM10, PM2.5, SO2, and NO2 concentrations. Calm and light air near the ground, weak precipitation, high daily maximum temperatures, and minimum relative humidity may provide favorable meteorological conditions for the accumulation of O3 precursors and photochemical reactions during the day, resulting in the daily peak values of O3 exceeding 160 μg/m3. The evolution of wind, relative humidity, and boundary layer height could play an important role in the variations in PM10 and PM2.5 concentrations by influencing pollutant accumulation or diffusion. It was suggested that the atmospheric structure of horizontal stability and vertical mixing below 1500 m could play a significant role in the accumulation and vertical distribution of ozone. The results highlight the important role of typhoons in the regional environment and provide a scientific basis for further application of multi-source observation data, as well as air pollution control.

The regional transport of air pollutants is an important process in determining regional air quality variations (Carroll & Dixon, 2002). In general, the atmospheric transport is mainly controlled by the vertical structure of the atmospheric boundary layer and atmospheric circulation. Globally, air pollutants can be transported from East Asia to North America (Y. Zhang et al., 2010).The wind near surface is important for air pollutant transport. The wind direction and speed largely affect the quantity and direction of transport (H. Wang et al., 2019). In the East Asia monsoon region, the prevailing wind directions are northeast during winter half year and southwest during summer half year. The large-scale weather systems, such as continental cold highs and tropical cyclones, would drive regional transport of air pollutants from seriously polluted areas to other areas in East Asia (Chen et al., 2014;Shan et al., 2009). Also, the transport sources and paths of downwind regions are different due to the seasonal variation of prevailing wind directions (Hagler et al., 2006). The Yangtze River Delta (YRD) and North China Plain (NCP) in East China are considered to be the major emission regions. In previous studies, the transport of pollutants from the YRD and NCP accounts for a large proportion of air pollution episodes in other regions of East China (Z. F. Wang et al., 2014). During a regional transport process, the NCP was considered to be a source region of the YRD (J. . Similarly, East China could contribute ∼100 μg•m −3 of PM 2.5 to Beijing (in NCP) with the continuous southerly wind in several winter haze episode during 2010(L. Zhang, Wang, et al., 2015. The transport within the NCP contributed 70% of the PM 2.5 to Beijing (L. . Even though high proportion of exogenous pollutants leads to several haze cases in East China, the secondary aerosol could generated and accumulate for local high concentration of PM 2.5 under stable meteorological conditions in such high-emission regions of the YRD and NCP (M.