Estimating Urban CH₄ Emissions From Satellite-Derived Enhancement Ratios of CH₄, CO₂, and CO
Creators
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1.
University of Toronto
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2.
Joint Research Centre
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3.
Princeton University
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4.
California Institute of Technology
Abstract
Urban centers are an important source of anthropogenic methane emissions and the focus of recent policy efforts aimed at emission reductions. But, emissions from urban areas are poorly characterized except in the few cities with robust measurement infrastructure. Satellite measurements offer a means for monitoring urban emissions. We use colocated measurements of methane (CH₄) and carbon monoxide (CO) from the TROPOspheric Monitoring Instrument (TROPOMI) and carbon dioxide (CO₂) from the Orbiting Carbon Observatory 2 and Orbiting Carbon Observatory 3 (OCO‐2/3) to calculate CH₄:CO₂, CH₄:CO, and CO:CO₂ enhancement ratios over 103 cities. We compare our enhancement ratios to those derived from ground‐based instruments in Los Angeles and find good agreement. Then, we combine our enhancement ratios with CO and inventories to calculate CH₄ emissions and find good agreement with estimates from past studies. Finally, we compare our satellite‐based enhancement ratios to those computed from the bottom‐up globally gridded emission inventories, and we find significant differences between them. Combining results from the three enhancement ratios, we find EDGARv8 to best represent CH₄ emissions in urban areas with mean errors of 34% compared to CAMS‐GLOB‐ANTv6.2 (based on EDGARv6.1), and CEDSv2021 with mean errors of 43% and 49%, respectively. These differences are largely driven by EDGARv8 changes in South‐Central and East Asia. We also find that EDGARv8 and HTAPv3 underestimate CO emissions by a factor of 2–5 for cities in Iran, Turkmenistan, and Argentina. Finally, we find that CO emissions are overestimated in some cities in Europe by a factor of ~2.
Copyright and License
© 2025. The Author(s). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Acknowledgement
The authors thank Oliver Schneising (University of Bremen) for useful comments on this manuscript and for developing the WFMD/TROPOMI data product. The authors also thank the rest of the WFMD/TROPOMI team. The authors thank Paul O. Wennberg (Caltech) for providing data from the Caltech TCCON station. The authors thank Joshua L. Laughner (JPL) for helpful discussions about NO₂ plumes. JPM was supported by the Canadian Space Agency fund 16SUASCOBF (Carbon monoxide in the Canadian boreal forest and urban centers), the Ontario Graduate Scholarship, and the Climate Positive Energy Climate Solutions Scholar Award at the University of Toronto. Development of the TROPOMI/WFMD product was supported by the European Space Agency via the projects GHG-CCI+, MethaneCAMP, and SMART-CH4 (ESA contract nos. 4000126450/19/I-NB, 4000137895/22/I-AG, and 4000142730/23/I-NS) and the Bundesministerium für Bildung und Forschung within its project ITMS (Grant 01 LK2103A). This publication contains modified Copernicus Sentinel data (2018–2023). Sentinel-5 Precursor is an ESA mission implemented on behalf of the European Commission. The TROPOMI payload is a joint development by ESA and the Netherlands Space Office (NSO). The Sentinel-5 Precursor ground-segment development has been funded by ESA and with national contributions from the Netherlands, Germany, and Belgium.
Data Availability
Satellite data are from TROPOMI/WFMD v1.8 (Schneising et al., 2023), TROPOMI NO₂ v2 (Copernicus Sentinel-5P (processed by ESA), 2021), OCO-2 v11.1r (OCO-2/OCO-3 Science Team et al., 2022a), and OCO-3 v10.4r (OCO-2/OCO-3 Science Team et al., 2022b). Caltech TCCON data are from GGG2020 (https://tccondata.org, Wennberg et al., 2022) and GGG2014 (Total Carbon Column Observing Network (TCCON) Team, 2017). City boundary data are from the Global Human Settlement Urban Centre Database R2019A v1.2 (Freire et al., 2019). Emissions data are from EDGARv8 (Crippa, Guizzardi, Schaaf, et al., 2023), CAMS-GLOB-ANTv6.2 (Granier et al., 2019; Soulie et al., 2024), CEDSv2021 (Ahsan et al., 2022), and HTAPv3 (Crippa, 2023; Crippa, Guizzardi, Butler, et al., 2023). Methane emission data are used for the United States (E. McDuffie et al., 2023) and Mexico (Scarpelli, Jacob, Octaviano Villasana et al., 2020). Temporal scaling factors are from CAMS-GLOB-TEMPOv3.1 (Guevara et al., 2020, 2021).
Supplemental Material
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JGR Atmospheres - 2025 - Mastrogiacomo - Estimating Urban CH4 text CH 4 Emissions From Satellite‐Derived.pdf
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Additional details
Related works
- Featured in
- Journal Issue: https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)2169-8996.CO2FROMSPACE (URL)
- Is supplemented by
- Supplemental Material: https://agupubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1029%2F2025JD043394&file=2025JD043394-sup-0004-Supporting+Information+SI-S01.pdf (URL)
Funding
- Canadian Space Agency
- 16SUASCOBF
- European Space Agency
- 4000126450/19/I-NB
- European Space Agency
- 4000137895/22/I-AG
- European Space Agency
- 4000142730/23/I-NS
- Federal Ministry of Education, Science and Research
- 01 LK2103A
Dates
- Accepted
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2025-06-22
- Available
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2025-07-05Version of record online