Tropical upper-tropospheric trends in ozone and carbon monoxide (2005–2020): observational and model results

Froidevaux, Lucien; Kinnison, Douglas E.; Gaubert, Benjamin; Schwartz, Michael J.; Livesey, Nathaniel J.; Read, William G.; Bardeen, Charles G.; Ziemke, Jerry R.; Fuller, Ryan A.

doi:https://doi.org/10.5194/acp-25-597-2025

Articles | Volume 25, issue 1

https://doi.org/10.5194/acp-25-597-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Tropospheric Ozone Assessment Report Phase II (TOAR-II) Community...

https://doi.org/10.5194/acp-25-597-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 1

Research article

|

17 Jan 2025

Research article |

| 17 Jan 2025

Tropical upper-tropospheric trends in ozone and carbon monoxide (2005–2020): observational and model results

Lucien Froidevaux, Douglas E. Kinnison, Benjamin Gaubert, Michael J. Schwartz, Nathaniel J. Livesey, William G. Read, Charles G. Bardeen, Jerry R. Ziemke, and Ryan A. Fuller

Supplement

https://doi.org/10.5194/acp-25-597-2025-supplement

Data sets

MLS/Aura Level 3 Monthly Binned Ozone (O$_3$) Mixing Ratio on Assorted Grids V005 M. Schwartz et al. https://doi.org/10.5067/Aura/MLS/DATA/3546

MLS/Aura Level 3 Monthly Binned Carbon Monoxide (CO) Mixing Ratio on Assorted Grids V005 M. Schwartz et al. https://doi.org/10.5067/Aura/MLS/DATA/3536

OMI CCD, OMI/MLS and OMPS/MERRA-2 data NASA https://acd-ext.gsfc.nasa.gov/Data_services/cloud_slice/

CESM2 data and software G. Danabasoglu https://doi.org/10.5065/D67H1H0V

CAM-chem and WACCM outputs B. Gaubert and D. Kinnison https://doi.org/10.5281/zenodo.14510410

MOPITT CO gridded daily means (Near and Thermal Infrared Radiances) V009 NASA/LARC/SD/ASDCMOPITT https://doi.org/10.5067/TERRA/MOPITT/MOP03JM.009

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Short summary

We compare observed changes in ozone (O₃) and carbon monoxide (CO) in the tropical upper troposphere (10–15 km altitude) for 2005–2020 to predictions from model simulations that track the evolution of natural and industrial emissions transported to this region. An increasing trend in measured upper-tropospheric O₃ is well matched by model trends. We find that changes in modeled industrial CO surface emissions lead to better model agreement with observed slight decreases in upper-tropospheric CO.