Tropospheric Ozone Assessment Report II: Past and present tropospheric ozone using satellite observations
Abstract
Satellite observations enable global assessments of ozone in the free troposphere, yet uncertainties in earlier records limited the first Tropospheric Ozone Assessment Report's (TOAR-I) confidence in regional distributions and, especially, decadal trends. Here, we leverage longer and improved satellite records, additional datasets and new harmonization approaches to provide a second, more confident, TOAR assessment of present-day and longer-term changes. We quantify the 2018-2022 climatology and seasonal cycle at 1∘×1∘ resolution and evaluate trends in a combined tropospheric column record since 2005. Summertime maxima exceed 50 DU over the Middle East, and annual-mean values exceed 40 DU from East Asia to the Mediterranean. The present-day global tropospheric ozone burden is 336±6 Tg. Decadal ozone changes are pronouncedly nonlinear: increases of 2-4.5% per decade during 2005-2019 occur over 20% of the globe (high confidence), most notably across Asia, followed by widespread declines after 2020, producing a net decrease since 2005 across 70% of the globe. Dynamical and episodic drivers, such as El Niño-Southern Oscillation, extreme wildfires, and the COVID-19 pandemic, strongly influenced variability, underscoring the sensitivity of tropospheric ozone to both natural and anthropogenic influences and the critical need for sustained, coordinated satellite monitoring. This article is part of the theme issue 'Tropospheric Ozone Assessment Report II'.
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Authors: Daan Hubert, Kazuyuki Miyazaki, Gaëlle Dufour, Elyse A. Pennington, Viktoria Sofieva, Carlo Arosio, Brice Barret, Anne Boynard, Melanie Coldewey‐Egbers, Juan Cuesta, Klaus-Peter Heue, Arno Keppens, N. A. Kramarova, Jean‐Christopher Lambert, Diego Loyola, Andrea P. Orfanoz-Cheuquelaf, Richard Siddans, Roeland Van Malderen, J. Pepijn Veefkind, Catherine Wespes, J. R. Ziemke
Institutions: Delft University of Technology, Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), Goddard Space Flight Center, Université Paris Cité, Sorbonne Université, Centre National de la Recherche Scientifique, University of Bremen, Université de Versailles Saint-Quentin-en-Yvelines, Université Paris-Est Créteil, Université Libre de Bruxelles, Rutherford Appleton Laboratory, Finnish Meteorological Institute, Université Toulouse III - Paul Sabatier, Royal Netherlands Meteorological Institute, Max Planck Institute for Meteorology, Jet Propulsion Laboratory, Institute of Solar-Terrestrial Physics, Hochschule Bremen, Morgan State University, Royal Belgian Institute for Space Aeronomy, Institut Pierre-Simon Laplace, Institute for Applied Systems Technology Bremen, Paris-Est Sup, Royal Meteorological Institute of Belgium, Laboratoire Interuniversitaire des Systèmes Atmosphériques, Laboratoire Techniques, Territoires et Sociétés