Impacts of Sea-Land Breeze on the Ozone Pollution under varied synoptic weather patterns in the Pearl River Delta, China

Ground-level ozone (O₃) pollution has become a critical environmental issue in coastal urban areas, driven by rapid global urbanization. Sea-land breeze (SLB) circulation plays a key role in this process. However, the combined effects of SLB and synoptic-scale weather systems on O₃ pollution remain poorly understood. Most existing studies focus on individual events or short-term periods, lacking a systematic analysis of how mesoscale SLB interacts with larger-scale weather patterns to influence O₃ concentrations.This study investigates the impacts of SLB on O₃ pollution in the Pearl River Delta (PRD), a densely populated coastal region in southern China. Using 28 years of observational data and ERA5 reanalysis datasets, we analyze the spatial and temporal variability of SLB and its interactions with synoptic-scale winds in shaping O₃ distributions. Additionally, a random forest model is applied to quantitatively assess the contributions of SLB to O₃ variations under different meteorological conditions.This research provides a systematic framework for understanding the mesoscale-synoptic coupling processes that drive O₃ pollution in coastal cities. The findings highlight the critical role of SLB in regulating regional air quality and offer a solid scientific basis for designing effective mitigation strategies in similar coastal urban regions worldwide.