J Environ Sci (China). 2026 May;163:811-822. doi: 10.1016/j.jes.2025.08.037. Epub 2025 Aug 23.
ABSTRACT
Ground-level ozone (O3) pollution has become increasingly prominent in coastal cities, where sea-land breeze (SLB) plays a crucial role. However, the impact mechanisms of SLB circulation on O3 pollution in coastal region remain not well understand, since the SLB influence always coupled with the synoptic-scale wind fields. Here, by using 28-year observational data and the ERA5 reanalysis dataset, we reveal significant spatial heterogeneity in the impacts of SLB across the Pearl River Delta regions. On the western bank, O3 concentrations are higher during SLB events compared to non-SLB periods under all synoptic weather patterns, since the SLB on the western bank predominantly occurs under low synoptic wind conditions, which also facilitates the O3 formation. Therefore, O3 pollution and the SLB event showed an adjoint relationship on the western bank, rather than the causation. On the eastern bank, O3 concentration had varied responses on SLB events under different synoptic weather patterns: The sea breeze from the south combined with the synoptic wind in the same direction led to enhanced atmospheric diffusion capacity, thereby reducing the O3 concentration; Once the synoptic wind is northeasterly, the counteraction between sea breezes and synoptic winds weakens dispersion conditions, resulting in O3 accumulation. Quantitative analysis using random forest modeling demonstrates that SLB changes O3 concentrations by -2.68 ppb (-8 %) under southerly weather patterns but increase by 11.51 ppb (20 %) under Northeasterly patterns on the eastern bank. We highlight the crucial regulatory role of mesoscale-synoptic scale coupling processes in regional O3 distribution.
PMID:41887899 | DOI:10.1016/j.jes.2025.08.037
