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Fossil Versus Nonfossil CO Sources in the US: New Airborne Constraints From ACT‐America and GEM
Author(s) -
Gonzalez Andres,
Millet Dylan B.,
Yu Xueying,
Wells Kelley C.,
Griffis Timothy J.,
Baier Bianca C.,
Campbell Patrick C.,
Choi Yonghoon,
DiGangi Joshua P.,
Gvakharia Alexander,
Halliday Hannah S.,
Kort Eric A.,
McKain Kathryn,
Nowak John B.,
Plant Genevieve
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl093361
Subject(s) - fossil fuel , environmental science , sink (geography) , atmospheric sciences , tracer , carbon monoxide , air pollution , pollution , geology , ecology , chemistry , geography , biochemistry , physics , cartography , nuclear physics , biology , catalysis
Carbon monoxide (CO) is an ozone precursor, oxidant sink, and widely used pollution tracer. The importance of anthropogenic versus other CO sources in the US is uncertain. Here, we interpret extensive airborne measurements with an atmospheric model to constrain US fossil and nonfossil CO sources. Measurements reveal a low bias in the simulated CO background and a 30% overestimate of US fossil CO emissions in the 2016 National Emissions Inventory. After optimization we apply the model for source partitioning. During summer, regional fossil sources account for just 9%–16% of the sampled boundary layer CO, and 32%–38% of the North American enhancement—complicating use of CO as a fossil fuel tracer. The remainder predominantly reflects biogenic hydrocarbon oxidation plus fires. Fossil sources account for less domain‐wide spatial variability at this time than nonfossil and background contributions. The regional fossil contribution rises in other seasons, and drives ambient variability downwind of urban areas.