Investigating ozone build-up in the east of England during the July 2015 heat wave

Details

• Journal Title:
  Science of The Total Environment
• Personal Author:
  Romero-Alvarez, Johana ; Lupaşcu, Aurelia ; Dorling, Steve ; Reeves, Claire E. ; Butler, Tim
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; CIRES (Cooperative Institute for Research in Environmental Sciences) ; GSL (Global Systems Laboratory)
• Description:
  Ozone (O₃) precursors controls have reduced peak episodes in the UK, yet some regions still exceed the 50 ppbv (8-h) limit under certain meteorological conditions. This study uses O₃-tagging within WRF-Chem to quantify NOₓ contributions to near-surface O₃ across the East of England during a short heatwave (30 June-5 July 2015), where O₃ peaked at 116 ppbv. Despite underestimating peak O₃, the model effectively captures the episode's evolution and spatial extent (MB: −2 ppbv, r: 0.78), depicting O₃ increases on the hottest days and their decline. During the peak O₃ event, Western Europe contributed ∼60 % of daily mean O₃, while domestic NOₓ emissions accounted for only ∼4.6 %. South-easterly winds transported O₃ and precursors from BENELUX, France, Germany, the North Sea, and the English Channel. Near-surface wind convergence (−0.00002 s −1) with weaker westerlies redirected domestic O₃ to the central UK, intensifying continental influence. Conversely, south-south-westerly flows amplified domestic O₃ contributions. Analysis of the processes contributing to O₃ build-up highlights that transboundary transport played a significant role during the peak event. Boundary layer growth contributed by entraining O₃-rich air (up to 10.3 ppb h −1 across the boundary layer top), along with precursors from the residual layer, facilitating their downward mixing to surface levels. This process set the stage for in-situ photochemical O₃ production, which peaked at midday, contributing to a total daily O₃ production of 42 ppbv on average across the region. Our findings underscore the necessity of coordinated international efforts to manage transboundary pollution, alongside targeted local measures to reduce O₃ precursor emissions. O₃-tagging in WRF-Chem quantifies NOₓ contributions to the observed O₃ build-up SE winds brought O₃ from Western EU (60 %), while UK NOₓ contributed 4.6 % Domestic sources had a greater impact on surface O₃ during south-southwesterly flows
• Source:
  Science of The Total Environment, 979, 179464
• DOI:
  https://doi.org/10.1016/j.scitotenv.2025.179464
• ISSN:
  0048-9697
• Format:
  pdf
• Publisher:
  Elsevier BV
• Pubmed ID:
  40267651
• Document Type:
  Journal Article
• Funding:
  Grant no. NA22OAR4320151
• License:
  https://creativecommons.org/licenses/by-nc/4.0/
• Rights Information:
  CC BY-NC
• Compliance:
  Library
• Download URL:
  https://repository.library.noaa.gov/view/noaa/74761/noaa_74761_DS1.pdf
• File Type:
  [PDF - 10.81 MB]
• Collection(s):
  Office of Oceanic and Atmospheric Research (OAR) ; NOAA Cooperative Institutes
• Main Document Checksum:
  urn:sha-512:c65bcd4958717818b937facf520e87cd3a01c3e3d77b13a69b3a8155630af58a0c69201283c771c11953b830a6a7e56064fc7b06b3906f8e7251eafa577388ae