Ground-based tropospheric ozone measurements: regional tropospheric ozone column trends from the TOAR-II/HEGIFTOM homogenized datasets
Journal article, 2025
Quantifying long-term free-tropospheric ozone trends is essential for understanding the impact of human activities and climate change on atmospheric chemistry. However, this is complicated by two key challenges: the differences among existing satellite-derived tropospheric ozone products, which are not yet fully understood or reconciled, and the limited temporal and spatial coverage of ground-based reference measurements. Here, we explore if a more consistent understanding of the geographical distribution of tropospheric ozone column (TrOC) trends can be obtained by focusing on regional trends from ground-based measurements. Regions were determined with a correlation analysis between modeled TrOCs at the site locations. For those regions, TrOC trends were estimated with quantile regression for the Trajectory-mapped Ozonesonde dataset for the Stratosphere and Troposphere (TOST) and with a linear mixed-effects modeling (LMM) approach to calculate synthesized trends from homogenized HEGIFTOM (Harmonization and Evaluation of Ground-based Instruments for Free-Tropospheric Ozone Measurements) individual site trends. For different periods (1990-2021/22, 1995-2021/22, 2000-2021/22), both approaches give increasing (partial) tropospheric ozone column amounts over almost all Asian regions (median confidence) and negative trends over Arctic regions (very high confidence). Trends over Europe and North America are mostly weakly positive (LMM) or negative (TOST). For both approaches, the 2000-2021/22 trends decreased in magnitude compared to 1995-2021/22 for most regions; and for all time periods and regions, the pre-COVID trends are larger than the post-COVID trends. Our results enable the validation of global satellite TrOC trends and assessment of the performance of atmospheric chemistry models to represent the distribution and variation of TrOC.
Author
Roeland Van Malderen
Royal Meteorological Institute of Belgium
Zhou Zang
University of Toronto
Kai-Lan Chang
National Oceanic and Atmospheric Administration
University of Colorado
Owen R. Cooper
National Oceanic and Atmospheric Administration
Eliane Maillard Barras
Federal Office of Meteorology and Climatology MeteoSwiss
Corinne Vigouroux
Belgian Institute for Space Aeronomy (BIRA-IASB)
Irina Petropavlovskikh
National Oceanic and Atmospheric Administration
University of Colorado
Thierry Leblanc
California Institute of Technology (Caltech)
Valerie Thouret
Paul Sabatier University
Pawel Wolff
Paul Sabatier University
Peter Effertz
National Oceanic and Atmospheric Administration
Audrey Gaudel
National Oceanic and Atmospheric Administration
University of Colorado
David W. Tarasick
Environment and Climate Change Canada
Herman G. J. Smit
Jülich Research Centre
Anne M. Thompson
University of Maryland
National Aeronautics and Space Administration (NASA)
Ryan M. Stauffer
National Aeronautics and Space Administration (NASA)
Debra E. Kollonige
National Aeronautics and Space Administration (NASA)
Science Systems and Applications, Inc.
Deniz Poyraz
Royal Meteorological Institute of Belgium
Gerard Ancellet
Univ Versailles St Quentin en Yvelines UVSQ
Marie-Renee De Backer
University Hospital of Reims
Matthias M. Frey
Karlsruhe Institute of Technology (KIT)
James W. Hannigan
National Center for Atmospheric Research
Jose L. Hernandez
Meteorological State Agency of Spain (AEMET)
Bryan J. Johnson
National Oceanic and Atmospheric Administration
Nicholas Jones
University of Wollongong
Rigel Kivi
Finnish Meteorological Institute (FMI)
Emmanuel Mahieu
University of Liège
Isamu Morino
National Institute for Environmental Studies of Japan
Katrin Mueller
Helmholtz Association of German Research Centres
Isao Murata
Tohoku University
Justus Notholt
Universität Bremen
Ankie Piters
Royal Netherlands Meteorological Institute
Maxime Prignon
Chalmers, Space, Earth and Environment, Geoscience and Remote Sensing
Richard Querel
National Institute of Water and Atmospheric Research (NIWA)
Vincenzo Rizi
University of L'Aquila
Dan Smale
National Institute of Water and Atmospheric Research (NIWA)
Wolfgang Steinbrecht
Deutscher Wetterdienst
Kimberly Strong
University of Toronto
Ralf Sussmann
Karlsruhe Institute of Technology (KIT)
Atmospheric Chemistry and Physics
1680-7316 (ISSN) 1680-7324 (eISSN)
Vol. 25 17 9905-9935Subject Categories (SSIF 2025)
Climate Science
Meteorology and Atmospheric Sciences
DOI
10.5194/acp-25-9905-2025