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

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 O₃ and PM_2.5. Our findings demonstrated that ARF fostered the accumulation of pollutants and moisture, initiating two distinct feedback mechanisms concerning O₃. The elevation in the NO/NO₂ ratio amplified O₃ consumption. Increased near-surface moisture diminished upper-level cloud formation, thereby enhancing photolysis rates and O₃ photochemical production. The pronounced impact of heightened NO/NO₂ on O₃ 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 O₃ and PM_2.5, except for an anomalous increase observed in summer, with O₃ increasing by 1.6 ppb and PM_2.5 by 2.5 μg m^-3. The heterogeneous absorption of hydroxides in spring, autumn, and winter predominantly governed the AHR-induced variation of O₃, leading to a decrease in O₃ by 0.7-1 ppb. Conversely, O₃ variations in summer were primarily dictated by O₃-sensitive chemistry, with heterogeneous absorption of NO_y catalyzing a decrease of 2.4 ppb in O₃. Furthermore, AHR accentuated PM_2.5 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 O₃, alleviating the secondary oxidation of PM_2.5 and leading to a decrease of 0.3 μg m^-3 in PM_2.5. Conversely, albeit aerosol substantially depleted O₃ by 0.4-4 ppb through their interactions except for summer, aerosol feedback on PM_2.5 was more pronounced, resulting in a significant increase of 1.7-6.1 μg m^-3 in PM_2.5. Our study underscored the seasonal disparities in the ramifications of multifaceted aerosol-ozone interplay on air quality.