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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BibTeX
@article{hubert2026tropospheric,
title = {{Tropospheric Ozone Assessment Report II: Past and present tropospheric ozone using satellite observations}},
author = {Daan Hubert and Kazuyuki Miyazaki and Gaëlle Dufour and Elyse Pennington and Viktoria Sofieva and Carlo Arosio and Brice Barret and Anne Boynard and Melanie Coldewey-Egbers and Juan Cuesta and Klaus-Peter Heue and Arno Keppens and Natalya Kramarova and Jean-Christopher Lambert and Diego Loyola and Andrea Orfanoz-Cheuquelaf and Richard Siddans and Roeland van Malderen and J. Pepijn Veefkind and Catherine Wespes and Jerry Ziemke},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
year = {2026},
month = oct,
doi = {10.1098/rsta.2025.0274},
url = {https://hal.science/hal-05843473v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Tropospheric Ozone Assessment Report II: Past and present tropospheric ozone using satellite observations
AU - Daan Hubert
AU - Kazuyuki Miyazaki
AU - Gaëlle Dufour
AU - Elyse Pennington
AU - Viktoria Sofieva
AU - Carlo Arosio
AU - Brice Barret
AU - Anne Boynard
AU - Melanie Coldewey-Egbers
AU - Juan Cuesta
AU - Klaus-Peter Heue
AU - Arno Keppens
AU - Natalya Kramarova
AU - Jean-Christopher Lambert
AU - Diego Loyola
AU - Andrea Orfanoz-Cheuquelaf
AU - Richard Siddans
AU - Roeland van Malderen
AU - J. Pepijn Veefkind
AU - Catherine Wespes
AU - Jerry Ziemke
PY - 2026
DA - 2026/10/26
JO - Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
DO - 10.1098/rsta.2025.0274
UR - https://hal.science/hal-05843473v1
AB - 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’.
SN - 1364-503X
SN - 1471-2962
ER -