Which aerosol type dominate the impact of aerosols on ozone via changing photolysis rates?

Aerosols can impact ozone via influencing photolysis rates. However, absorbing aerosols (AA) and scattering aerosols (SA) show different optical properties that impact ozone differently. It’s noteworthy that previous studies on the impact of SA have not reached a consistent conclusion, leading to the disconfirmation of which type of aerosol dominates the impact of aerosols on ozone via influencing photolysis rates. In this study, we found that SA can decrease the chemical production of ozone (CHEM) near surface but significantly increase that aloft, then enhancing the vertical exchange of ozone. In this case, the strong vertical exchange neutralizes the opposite changes in CHEM and ultimately lead to very slight changes in ozone, suggesting AA dominates the impact of aerosols on ozone via influencing photolysis rates. It shows a quadratic relationship that reducing AA could lead to a nonlinear increase in surface ozone (ΔO₃). More than 86% of the North China Plain would experience ΔO₃ when reducing more than 3/4 of AA, especially in urban areas, the increment could be more than 5 ppb. Our results suggest that more attention should be paid on the balance between ozone and AA when determining the synergetic control policy of air quality in China.