EGU23-1453, updated on 08 May 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Response of the ozone chemistry to changes in emissions over the Catalonia region

Alba Badia1, Veronica Vidal1,2, Sergi Ventura1, Roger Curcoll3, Ricard Segura1, and Gara Villalba4
Alba Badia et al.
  • 1Sostenipra Research Group, Institute of Environmental Sciences and Technology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
  • 2Departament d’Arquitectura de Computadors i Sistemes Operatius (CAOS), Escola d’Enginyeria, Universitat Autònoma de Barcelona 08193 Bellaterra, Barcelona, Spain.
  • 3Institut de Tècniques Energètiques (INTE), Universitat Politècnica de Catalunya, Barcelona, Spain
  • 4Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain

Tropospheric ozone (O3) is an important surface pollutant in urban areas with complex formation mechanisms that depend on the atmospheric chemistry composition and meteorological factors. The severe reduction in anthropogenic emissions during the COVID-19 pandemic can serve to further our understanding of the photochemical mechanisms that lead to O3 formation to provide guidance for policy aiming to reduce air pollution. In this study we use the air quality model WRF-Chem coupled with the urban canopy model BEP-BEM to investigate changes in the ozone chemistry over the Metropolitan Area of Barcelona (AMB) and its atmospheric plume northward, which is responsible for the highest number of hourly O3 exceedances in Spain. The aim is to investigate the response of the ozone chemistry to changes in precursor emissions. Results show that with the reduction in emissions: 1) the ozone chemistry formation tends to go to the NOx-limited or transition regimes, however urban areas over highly polluted areas are still in the VOC-limited regime, 2) the reduced O3 production is overwhelmed by the less nitric oxide (NO) titration resulting in a net increase of O3 concentration (up to 20 %) in the afternoon, 3) the increase in maximum O3 (up to 6%) during the lockdown could be attributed to an enhancement in the atmospheric oxidation capacity, 4) ozone and odd oxygen (Ox) maximum levels generally decrease (up to 4 %) in the relaxation period with a reduced atmospheric oxidation capacity (AOC), indicating an improvement of the air quality, and, 5) changes in ozone concentrations in the AMB contribute to the pollution plume along the S–N valley to the Pyrenees. Our results indicates that a protocol with strict measures to control NOx emissions, without cutting significantly anthropogenic sources of VOCs (e.g. for power plants and heavy industry) is essential for O3 abatement plans. In addition, our results show that the design of a mitigation strategy to reduce O3 cannot be related only on emissions reductions because ozone chemistry depends on several other factors (AOC, ozone regimes, local meteorology, transport).

How to cite: Badia, A., Vidal, V., Ventura, S., Curcoll, R., Segura, R., and Villalba, G.: Response of the ozone chemistry to changes in emissions over the Catalonia region, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1453,, 2023.

Supplementary materials

Supplementary material file