Aerosol Radiation Effect Outweighs VOCs Reactivity Effect on Vertical Ozone Photochemical Features

Abstract

The proportion of more active volatile organic compounds (VOCs) species decreases with altitude, whereas radiation increases vertically due to aerosol scattering near the surface, exerting opposite effects on vertical O₃ generation. Using the observation-based model (OBM) constrained by vertical profiles, we identified that the aerosol radiation effect (ARE) has a stronger impact on photochemical characteristics and O₃-NOx-VOC sensitivity than the VOCs reactivity effect (VRE). ARE is the dominant factor, promoting the formation of O₃ and ·OH (increases by 36.7% and 106.3%), enhancing high-altitude oxidation, and shifting parts of the VOC-limited regimes to the NOx-limited regimes (VOCs/NOx ratio decreases by 21.1%). Additionally, rapid NOx depletion with altitude leads to stronger NOx limitation aloft, amplifying ARE's effect on O₃-NOx-VOC sensitivity (ratio decreases by 28.1%). These findings improve the understanding of vertical ozone generation conditions and suggest that more attention should be paid to vertical environments in surface ozone management.