Deciphering the seasonal dynamics of multifaceted aerosol-ozone interplay: Implications for air quality management in Eastern China.

We employed an enhanced WRF-Chem to investigate the discrete mechanisms of aerosol-radiation-feedback (ARF), extinction-photochemistry (AEP), and heterogeneous-reactions (AHR) across different seasons in eastern China, aiming to assess the synergistic effects arising from the simultaneous operation of multiple processes on O and PM. Our findings demonstrated that ARF fostered the accumulation of pollutants and moisture, initiating two distinct feedback mechanisms concerning O. The elevation in the NO/NO ratio amplified O consumption. Increased near-surface moisture diminished upper-level cloud formation, thereby enhancing photolysis rates and O photochemical production. The pronounced impact of heightened NO/NO on O led to a decrease of 0.1-2.7 ppb. When decoupled from ARF, AEP led to a more significant reduction in photolysis rates, resulting in declines in both O and PM, except for an anomalous increase observed in summer, with O increasing by 1.6 ppb and PM by 2.5 μg m. The heterogeneous absorption of hydroxides in spring, autumn, and winter predominantly governed the AHR-induced variation of O, leading to a decrease in O by 0.7-1 ppb. Conversely, O variations in summer were primarily dictated by O-sensitive chemistry, with heterogeneous absorption of NO catalyzing a decrease of 2.4 ppb in O. Furthermore, AHR accentuated PM by facilitating the formation of fine sulfates and ammonium while impeding nitrate formation. In summer, the collective impact of ARF, AEP, and AHR (ALL) led to a substantial reduction of 6.2 ppb in O, alleviating the secondary oxidation of PM and leading to a decrease of 0.3 μg m in PM. Conversely, albeit aerosol substantially depleted O by 0.4-4 ppb through their interactions except for summer, aerosol feedback on PM was more pronounced, resulting in a significant increase of 1.7-6.1 μg m in PM. Our study underscored the seasonal disparities in the ramifications of multifaceted aerosol-ozone interplay on air quality.