A high-resolution satellite-based map of global methane emissions reveals missing wetland, fossil fuel, and monsoon sources
<p>We interpret space-borne observations from the TROPOspheric Monitoring Instrument (TROPOMI) in a multi-inversion framework to characterize the 2018–2019 global methane budget. Evaluation of the inverse solutions indicates that simultaneous source <span class="inline-formula">...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/3325/2023/acp-23-3325-2023.pdf |
| Summary: | <p>We interpret space-borne observations from the
TROPOspheric Monitoring Instrument (TROPOMI) in a multi-inversion framework
to characterize the 2018–2019 global methane budget. Evaluation of the
inverse solutions indicates that simultaneous source <span class="inline-formula">+</span> sink optimization
using methane observations alone remains an ill-posed problem – even with
the dense TROPOMI sampling coverage. Employing remote carbon monoxide (CO)
and hydroxyl radical (OH) observations with independent methane measurements
to distinguish between candidate solutions, we infer from TROPOMI a global
methane source of 587 (586–589) Tg yr<span class="inline-formula"><sup>−1</sup></span> and sink of 571 Tg yr<span class="inline-formula"><sup>−1</sup></span> for our analysis
period. We apply a new downscaling method to map the derived monthly
emissions to 0.1<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 0.1<span class="inline-formula"><sup>∘</sup></span> resolution, using the
results to uncover key gaps in the prior methane budget. The TROPOMI data
point to an underestimate of tropical wetland emissions (a posteriori increase
of <span class="inline-formula">+</span>13 % [6 %–25 %] or 20 [7–25] Tg yr<span class="inline-formula"><sup>−1</sup></span>), with adjustments following
regional hydrology. Some simple wetland parameterizations represent these
patterns as accurately as more sophisticated process-based models. Emissions
from fossil fuel activities are strongly underestimated over the Middle East
(<span class="inline-formula">+</span>5 [2–6] Tg yr<span class="inline-formula"><sup>−1</sup></span> a posteriori increase) and over Venezuela. The TROPOMI
observations also reveal many fossil fuel emission hotspots missing from the
prior inventory, including over Mexico, Oman, Yemen, Turkmenistan, Iran,
Iraq, Libya, and Algeria. Agricultural methane sources are underestimated in
India, Brazil, the California Central Valley, and Asia. Overall,
anthropogenic sources worldwide are increased by <span class="inline-formula">+</span>19 [11–31] Tg yr<span class="inline-formula"><sup>−1</sup></span> over
the prior estimate. More than 45 % of this adjustment occurs over India
and Southeast Asia during the summer monsoon (<span class="inline-formula">+</span>8.5 [3.1–10.7] Tg in
July–October), likely due to rainfall-enhanced emissions from rice, manure, and
landfills/sewers, which increase during this season along with the natural
wetland source.</p> |
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| ISSN: | 1680-7316 1680-7324 |