Multi-year dual-isotope fingerprinting at South Asian receptor sites constrain carbon monoxide sources and enhanced oxidation
| Published | 14 March 2026 |
|---|---|
| Publisher | Copernicus GmbH |
| DOI | 10.5194/egusphere-egu26-12027 |
Open access (gold)
Carbonaceous aerosols: black carbon and brown carbon Mitigation and filtration materials
Abstract
Carbon monoxide (CO) is an indirect short-lived climate forcer with uncertainties both in sources and its role in atmospheric oxidation. Based on nine winter-long dual-isotope campaigns at two South Asian receptor sites intercepting the continental outflow, we quantified CO source contributions and emission–sink dynamics. Combustion accounts for 68–74% of South Asia regional CO (including 34–37% from biomass burning) with secondary atmospheric oxidation contributing 26–32% (dominated by oxidation of non-methane volatile organic compounds NMVOCs at 21–26% with methane oxidation contributing 5.5–6.4%). These isotope-observational constraints suggest a twice higher role for atmospheric oxidation than in model estimates. Spatially, the absolute contributions of both primary and secondary CO decrease from the Indo-Gangetic Plain (IGP) to the northern Indian Ocean, indicating enhanced oxidation near source regions, while the relative contribution of secondary CO increases. Observation-model comparison suggests that continental transport dominates CO over adjacent oceanic regions, while local production is minor. During the COVID-19 pandemic, combustion-derived CO fell sharply, NMVOC-derived CO rose, and CH4-derived CO remained stable, suggesting enhanced oxidation from reduced competition among precursors. Our results reveal a far greater contribution of CO from atmospheric oxidation in South Asia than in current model estimates, highlighting the need for sustained emission controls to deliver concurrent climate and health benefits.
Abstract © the authors, published under a CC BY licence.
Cite this
Peng Yao, Henry Holmstrand, Carina van der Veen, Maria Elena Popa, Chloe A. Brashear, Krishnakant Budhavant, Mohanan Remani Manoj, Joakim Romson, Abdus Salam, Thomas Röckmann, Örjan Gustafsson (2026). Multi-year dual-isotope fingerprinting at South Asian receptor sites constrain carbon monoxide sources and enhanced oxidation. Copernicus GmbH. https://doi.org/10.5194/egusphere-egu26-12027
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