EMS Annual Meeting Abstracts
Vol. 18, EMS2021-469, 2021
https://doi.org/10.5194/ems2021-469
EMS Annual Meeting 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Response of surface ozone concentration to emission reduction and meteorology during the COVID-19 lockdown

Adrien Deroubaix1, Benjamin Gaubert2, Idir Bouarar1, Thierno Doumbia3, Yiming Liu4, Trissevgeni Stavrakou5, Sabine Darras6, Nellie Elguindi3, Claire Granier3,7, Forrest Lacey2, Jean-François Müller5, Xiaoqin Shi1, Simone Tilmes2, Tao Wang5, and Guy Brasseur1,2,4
Adrien Deroubaix et al.
  • 1Environmental Modeling Group, Max Planck Institute for Meteorology, Hamburg, Germany
  • 2Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, USA
  • 3Laboratoire d’Aérologie, Université de Toulouse, Toulouse, France
  • 4Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
  • 5Royal Belgian Institute for Space Aeronomy, Brussels, Belgium
  • 6Observatoire Midi-Pyrénées, Toulouse, France
  • 7NOAA Chemical Sciences Laboratory, University of Colorado, Boulder, USA

During the COVID-19 pandemic, the first lockdown period (March-May 2020) has led to an unprecedented reduction in pollutant emissions. For 3⁄4 of the more than 1,100 available monitoring stations in Europe, the average NO2 concentrations decreased by at least 25% (2.7 μg.m-3) compared to the average concentrations recorded during the same period of the previous seven years. The relative reduction was of similar magnitude in both urban and rural areas.

We further investigate the spatial distribution of the O3 change. Relative to the seven years average, positive anomalies were observed in northern Europe and negative anomalies in southwestern Europe. However, the level of total oxidant (Ox = O3 + NO2) remained unchanged except in southwestern Europe where it decreased.

At the global scale, the ozone concentration increased only in a few NOx-saturated regions. After presenting data from monitoring stations in Europe, we analyze the drivers of the change in surface ozone concentrations using the global Community Earth System Model. We contrast global simulations of the atmospheric composition with and without lockdown adjusted anthropogenic emissions for the COVID-19 period.

By comparing the situation in Europe with that of the United States and China, we show that the reduced cloudiness in northern Europe played a significant role by shifting the photochemical partitioning between NO2 and O3 toward more ozone, while in the North China Plain, enhanced ozone concentrations resulted primarily from reduced emissions of primary pollutants.

These results illustrate the complexity of the processes affecting ozone in the troposphere and hence the difficulty of implementing efficient regulations targeting air quality impacts.

How to cite: Deroubaix, A., Gaubert, B., Bouarar, I., Doumbia, T., Liu, Y., Stavrakou, T., Darras, S., Elguindi, N., Granier, C., Lacey, F., Müller, J.-F., Shi, X., Tilmes, S., Wang, T., and Brasseur, G.: Response of surface ozone concentration to emission reduction and meteorology during the COVID-19 lockdown, EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-469, https://doi.org/10.5194/ems2021-469, 2021.

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