Contrasting Mechanisms of Heatwave‐Ozone Pollution Compound Events and Independent Heatwave Events in the Yangtze River Delta
4 affiliations
- 1Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences Fudan University Shanghai China
- 2Shanghai Key Laboratory of Ocean‐land‐atmosphere Boundary Dynamics and Climate Change Shanghai China
- 3Key Laboratory of Polar Atmosphere‐ocean‐ice System for Weather and Climate Ministry of Education Fudan University Shanghai China
- 4Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences Integrated Research on Disaster Risk (IRDR) International Centre of Excellence (ICoE) on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health Fudan University Shanghai China
Abstract
Heat waves do not always coincide with ozone pollution, yet the mechanisms controlling their divergence remain insufficiently understood. Here, we investigate why some heat waves evolved into heatwave‐ozone pollution compound events (HWOP), whereas others remained isolated heat wave events (IHW), over the Yangtze River Delta during summer 2024. Using surface ozone observations and WRF‐CMAQ simulations, we identified HWOP and IHW events and examined their large‐scale circulation, lower‐tropospheric structure, and process‐level ozone tendencies. Both event types occurred under large‐scale warm anomalies associated with the westward extension of the Western Pacific Subtropical High and the eastward expansion of the South Asian High. Their ozone responses diverged, however, because of contrasting boundary‐layer meteorological conditions. Compared with HWOP, IHW was characterized by stronger ventilation and larger nighttime wind shear, which favored pollutant dispersion and more active vertical exchange. Process diagnostics further indicated that the divergence between HWOP and IHW was governed primarily by the balance between daytime photochemical production and nocturnal chemical loss. Compared to HWOP, IHW exhibited higher nocturnal near‐surface NO x and stronger ozone destruction, pointing to more effective nighttime titration and less favorable conditions for ozone persistence. In contrast, sustained ozone pollution during HWOP was associated with stronger daytime chemical production and weaker nocturnal removal. These results demonstrate that extreme heat alone is insufficient to produce ozone pollution; rather, the coupling between boundary‐layer structure and ozone chemical loss determines whether heat waves amplify surface ozone.
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BibTeX
@article{pan2026contrasting,
title = {{Contrasting Mechanisms of Heatwave‐Ozone Pollution Compound Events and Independent Heatwave Events in the Yangtze River Delta}},
author = {Jiaying Pan and Z Huang and Huiling Ouyang and Xiaoyan Wang},
journal = {Journal of Geophysical Research Atmospheres},
year = {2026},
month = may,
doi = {10.1029/2025jd045802},
url = {https://doi.org/10.1029/2025jd045802},
note = {CC BY},
}
RIS
TY - JOUR
TI - Contrasting Mechanisms of Heatwave‐Ozone Pollution Compound Events and Independent Heatwave Events in the Yangtze River Delta
AU - Jiaying Pan
AU - Z Huang
AU - Huiling Ouyang
AU - Xiaoyan Wang
PY - 2026
DA - 2026/05/30
JO - Journal of Geophysical Research Atmospheres
DO - 10.1029/2025jd045802
UR - https://doi.org/10.1029/2025jd045802
AB - Heat waves do not always coincide with ozone pollution, yet the mechanisms controlling their divergence remain insufficiently understood. Here, we investigate why some heat waves evolved into heatwave‐ozone pollution compound events (HWOP), whereas others remained isolated heat wave events (IHW), over the Yangtze River Delta during summer 2024. Using surface ozone observations and WRF‐CMAQ simulations, we identified HWOP and IHW events and examined their large‐scale circulation, lower‐tropospheric structure, and process‐level ozone tendencies. Both event types occurred under large‐scale warm anomalies associated with the westward extension of the Western Pacific Subtropical High and the eastward expansion of the South Asian High. Their ozone responses diverged, however, because of contrasting boundary‐layer meteorological conditions. Compared with HWOP, IHW was characterized by stronger ventilation and larger nighttime wind shear, which favored pollutant dispersion and more active vertical exchange. Process diagnostics further indicated that the divergence between HWOP and IHW was governed primarily by the balance between daytime photochemical production and nocturnal chemical loss. Compared to HWOP, IHW exhibited higher nocturnal near‐surface NO x and stronger ozone destruction, pointing to more effective nighttime titration and less favorable conditions for ozone persistence. In contrast, sustained ozone pollution during HWOP was associated with stronger daytime chemical production and weaker nocturnal removal. These results demonstrate that extreme heat alone is insufficient to produce ozone pollution; rather, the coupling between boundary‐layer structure and ozone chemical loss determines whether heat waves amplify surface ozone.
SN - 0148-0227
SN - 2156-2202
SN - 2169-897X
SN - 2169-8996
ER -