Ozone Anomalies in the Free Troposphere During the COVID-19 Pandemic

Idir Bouarar, Benjamin Gaubert, Guy P. Brasseur, Wolfgang Steinbrecht, Thierno Doumbia, Simone Tilmes, Yiming Liu, Trissevgeni Stavrakou, Adrien Deroubaix, Sabine Darras, Claire Granier, Forrest Lacey, Jean François Müller, Xiaoqin Shi, Nellie Elguindi, Tao Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

21 Citations (Scopus)


Using the CAM-chem Model, we simulate the response of chemical species in the free troposphere to scenarios of primary pollutant emission reductions during the COVID-19 pandemic. Zonally averaged ozone in the free troposphere during Northern Hemisphere spring and summer is found to be 5%–15% lower than 19-yr climatological values, in good agreement with observations. About one third of this anomaly is attributed to the reduction scenario of air traffic during the pandemic, another third to the reduction scenario of surface emissions, the remainder to 2020 meteorological conditions, including the exceptional springtime Arctic stratospheric ozone depletion. For the combined emission reductions, the overall COVID-19 reduction in northern hemisphere tropospheric ozone in June is less than 5 ppb below 400 hPa, but reaches 8 ppb at 250 hPa. In the Southern Hemisphere, COVID-19 related ozone reductions by 4%–6% were masked by comparable ozone increases due to other changes in 2020.

Original languageEnglish
Article numbere2021GL094204
JournalGeophysical Research Letters
Issue number16
Publication statusPublished - 28 Aug 2021


  • COVID pandemic
  • free troposphere
  • ozone

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


Dive into the research topics of 'Ozone Anomalies in the Free Troposphere During the COVID-19 Pandemic'. Together they form a unique fingerprint.

Cite this