Targeted emission controls for ozone pollution mitigation based on mesoscale weather pattern classifications in China’s Pearl River Delta region

Abstract

Surface ozone pollution in the Pearl River Delta (PRD) is strongly modulated by mesoscale weather patterns (MWPs), which govern the emission, transport, and chemical evolution of ozone and its precursors. To develop weather-specific control strategies, we used unsupervised classification to identify four characteristic MWPs associated with ozone exceedance days in the PRD during 2015–2023: spring/fall convergence between inland and coastal flow near the PRD estuary (MWP-1), spring coastal convergence between inland flow and sea breeze (MWP-2), summer/early-fall warm stagnant conditions under the Subtropical High (MWP-3), and summer/early-fall weak northerlies under typhoon influence (MWP-4). MWP-3 accounted for the largest share of exceedance days (35.4%), whereas MWP-4 led to the highest regional mean MDA8 ozone concentration (153.5 µg/m³). Using adjoint sensitivity modeling for representative ozone episodes in Shenzhen, we quantified ozone responses to precursor emissions under each MWP. Industry and transportation were identified as the dominant anthropogenic sectors, with ship emissions contributing under certain MWPs. Key precursor groups consistently included alkenes, alkanes, aromatics, and CO. Moreover, emissions beyond PRD and from the preceding day also contributed substantially to ozone exceedance in Shenzhen. A 10% reduction in emissions from targeted areas, sectors, and precursors lowered daytime ozone in Shenzhen by 4.1–5.9 µg/m³, compared with 1.1–2.1 µg/m³ for a uniform 10% reduction of anthropogenic precursor emissions within the PRD. These findings demonstrate a weather-aware framework for air quality management to optimize emission control and improve ozone mitigation in the PRD and other regions with similar meteorology–pollution linkages.

Graphical abstract

Keywords

Ozone / mesoscale weather / emission control strategy / unsupervised machine learning / adjoint modeling

Highlight

	● Four distinct mesoscale weather patterns were linked to PRD ozone exceedance.
	● Subtropical-High stagnation caused the most exceedance days in the PRD.
	● Typhoon-influenced northerlies produced the highest ozone levels in the PRD.
	● MWP-specific targeted emission reduction effectively mitigated ozone exceedance.

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