COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere
Wolfgang Steinbrecht, Dagmar Kubistin, C. Plaß-Dülmer, J. Davies, D. W. Tarasick, Peter von der Gathen, Holger Deckelmann, Nis Jepsen, Rigel Kivi, Norrie Lyall, Matthias Palm, Justus Notholt, B. Kois, Peter Oelsner, Marc Allaart, Ankie Piters, Michael B. Gill, Roeland Van Malderen, Andy Delcloo, Ralf Sussmann, Emmanuel Mahieu, Christian Servais, Gonzague Romanens, René Stübi, G. Ancellet, Sophie Godin‐Beekmann, Shoma Yamanouchi, Kimberly Strong, B. J. Johnson, Patrick Cullis, Irina Petropavlovskikh, James W. Hannigan, Jose‐Luis Hernandez, Ana Diaz Rodriguez, Tatsumi Nakano, Fernando Chouza, Thierry Leblanc, Carlos Torres, Omaira García, Amelie N. Röhling, Matthias Schneider, Thomas Blumenstock, Matthew B. Tully, Clare Paton‐Walsh, Nicholas Jones, Richard Querel, S. E. Strahan, Ryan M. Stauffer, Anne M. Thompson, Antje Inness, Richard Engelen, Kai‐Lan Chang, Owen R. Cooper
Abstract
Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 nmol/mol) below the 2000-2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere contributed less than one-quarter of the observed tropospheric anomaly. The observed anomaly is consistent with recent chemistry-climate model simulations, which assume emissions reductions similar to those caused by the COVID-19 crisis. COVID-19 related emissions reductions appear to be the major cause for the observed reduced free tropospheric ozone in 2020.