High-resolution inversion of methane emissions in the Southeast US using SEAC4RS aircraft observations of atmospheric methane: anthropogenic and wetland sources

We use observations of boundary layer methane from the SEAC4RS aircraft campaign over the Southeast US in August–September 2013 to estimate methane emissions in that region through an inverse analysis with up to 0.25∘×0.3125∘ (25×25 km2) resolution and with full error characterization. The Southeast...

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Bibliographic Details
Published in:Atmospheric chemistry and physics 2018-05, Vol.18 (9), p.6483-6491
Main Authors: Jian-Xiong, Sheng, Jacob, Daniel J, Turner, Alexander J, Maasakkers, Joannes D, Sulprizio, Melissa P, Bloom, A Anthony, Andrews, Arlyn E, Wunch, Debra
Format: Article
Language:English
Subjects:
Airborne observation
Aircraft
Aircraft observations
Anthropogenic factors
Atmospheric methane
Boundary layers
Carbon footprint
Emission
Emission inventories
Gas production
Greenhouse effect
Greenhouse gases
Land cover
Methane
Methane emissions
Oil and gas production
Resolution
Wetlands
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Summary:We use observations of boundary layer methane from the SEAC4RS aircraft campaign over the Southeast US in August–September 2013 to estimate methane emissions in that region through an inverse analysis with up to 0.25∘×0.3125∘ (25×25 km2) resolution and with full error characterization. The Southeast US is a major source region for methane including large contributions from oil and gas production and wetlands. Our inversion uses state-of-the-art emission inventories as prior estimates, including a gridded version of the anthropogenic EPA Greenhouse Gas Inventory and the mean of the WetCHARTs ensemble for wetlands. Inversion results are independently verified by comparison with surface (NOAA/ESRL) and column (TCCON) methane observations. Our posterior estimates for the Southeast US are 12.8±0.9 Tga-1 for anthropogenic sources (no significant change from the gridded EPA inventory) and9.4±0.8 Tga-1 for wetlands (27 % decrease from the mean in the WetCHARTs ensemble). The largest source of error in the WetCHARTs wetlands ensemble is the land cover map specification of wetland areal extent. Our results support the accuracy of the EPA anthropogenic inventory on a regional scale but there are significant local discrepancies for oil and gas production fields, suggesting that emission factors are more variable than assumed in the EPA inventory.
ISSN:1680-7316
1680-7324
DOI:10.5194/acp-18-6483-2018