Tropospheric Ozone Assessment Report II: Ozone distribution and variability in the oceanic and polar regions

Oceanic and polar regions are critical for global atmospheric processes, but an evaluation of ozone distributions and trends in these regions has been missing. In this assessment, part of the TOAR-II project, we report lower atmosphere ozone concentrations over open oceans and polar regions: with data from ships, buoys, aircraft and ground sites from 1975 to 2023, this is the most comprehensive dataset yet. Ozone trends were determined using Linear Mixed-effects Modelling (LMM). In most regions, trends have been modest since the mid-1970s (<1 nmol mol-1 per decade), positive in the mid-latitudes and tropical regions (with medium-low certainty), negative in the North and Tropical Pacific (with low and high certainty, respectively), increasing in Antarctica and decreasing in the Arctic. Seasonal effects often influence the long-term trends in extra-tropical regions. Five global and one hemispheric models were used to aid the interpretation of the sparse observations. The seasonal cycles are reasonably well reproduced, although models disagree with each other and with the observations on the distribution of ozone, especially in the tropics and in the Arctic. Changes in methane, iodine, shipping emissions, nitrogen oxides emissions, and terrestrial and marine volatile organic compound are likely to be important drivers for ozone over the oceans, although specific attributions are uncertain owing to insufficient data. This article is part of the theme issue 'Tropospheric Ozone Assessment Report II'.

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Journal
Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences
Published
2026-10-26
DOI
https://doi.org/10.1098/rsta.2025.0269
Primary Topic
Atmospheric Ozone and Climate
Type
article
Field-Weighted Citation Impact
0.00

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article

Tropospheric Ozone Assessment Report II: Ozone distribution and variability in the oceanic and polar regions

Fernando Iglesias‐Suarez, Marios Panagi, Matthew Rowlinson, Jesper Heile Christensen et al.
Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences
Atmospheric Ozone and Climate
article

Tropospheric Ozone Assessment Report II: Ozone distribution and variability in the oceanic and polar regions

Fernando Iglesias‐Suarez, Marios Panagi, Matthew Rowlinson, Jesper Heile Christensen, Mariano Mertens, Yugo Kanaya, J.A. Adame, Anne Mee Thompson, Alfonso Saiz‐Lopez, Maria Rosa Russo, Takashi Sekiya, Patrick Jöckel, Theodore K. Koenig, Ulaş İm, Andrea Mazzeo, Roberto Sommariva, Alba Badía, Debra E. Kollonige, Katie Read, Kenjiro Toyota, Ryan Michael Stauffer, Nathan Luke Abraham, Kai‐Lan Chang, Raeesa Moolla, Wanmin Gong
article en

Abstract

Oceanic and polar regions are critical for global atmospheric processes, but an evaluation of ozone distributions and trends in these regions has been missing. In this assessment, part of the TOAR-II project, we report lower atmosphere ozone concentrations over open oceans and polar regions: with data from ships, buoys, aircraft and ground sites from 1975 to 2023, this is the most comprehensive dataset yet. Ozone trends were determined using Linear Mixed-effects Modelling (LMM). In most regions, trends have been modest since the mid-1970s (<1 nmol mol-1 per decade), positive in the mid-latitudes and tropical regions (with medium-low certainty), negative in the North and Tropical Pacific (with low and high certainty, respectively), increasing in Antarctica and decreasing in the Arctic. Seasonal effects often influence the long-term trends in extra-tropical regions. Five global and one hemispheric models were used to aid the interpretation of the sparse observations. The seasonal cycles are reasonably well reproduced, although models disagree with each other and with the observations on the distribution of ozone, especially in the tropics and in the Arctic. Changes in methane, iodine, shipping emissions, nitrogen oxides emissions, and terrestrial and marine volatile organic compound are likely to be important drivers for ozone over the oceans, although specific attributions are uncertain owing to insufficient data. This article is part of the theme issue 'Tropospheric Ozone Assessment Report II'.

Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering SciencesVol. 384(2332)
Roskilde University (DK), Goddard Space Flight Center (US), Japan Agency for Marine-Earth Science and Technology (JP), Environment and Climate Change Canada (CA), Consejo Superior de Investigaciones Científicas (ES), Cyprus Institute (CY), University of Leicester (GB), Cooperative Institute for Research in Environmental Sciences (US), University of Colorado Boulder (US), University of the Witwatersrand (ZA), Hong Kong University of Science and Technology (HK), Aarhus University (DK), University of Cambridge (GB), Barcelona Supercomputing Center (ES), Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (DE), University College Birmingham (GB), Ta Solutions (China) (CN), National Centre for Atmospheric Science (GB), Instituto Nacional de Técnica Aeroespacial (ES), NOAA Chemical Sciences Laboratory (US), Instituto de Química Física Blas Cabrera (ES), NASA Earth Science (US), Predictia Intelligent Data Solutions SL (Spain) (ES), École Polytechnique Fédérale de Lausanne (CH), University of York (GB), Lancaster University (GB), University of Maryland, Baltimore County (US), University of Birmingham (GB), University of Hong Kong (HK), Universitat Politècnica de Catalunya (ES), Delft University of Technology (NL)
European Commission, Met Office, Ministry of Education, Culture, Sports, Science and Technology, Natural Environment Research Council, Japan Society for the Promotion of Science
Openalex Percentile: Top 21%
Atmospheric Ozone and Climate
DOIOpen Access PDFOpenAlex
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