Faculty Publications
Document Type
Article
Publication Version
Published Version
Journal/Book/Conference Title
Atmospheric Chemistry and Physics
Volume
21
Issue
2
First Page
951
Last Page
971
Abstract
We apply airborne measurements across three seasons (summer, winter and spring 2017-2018) in a multi-inversion framework to quantify methane emissions from the US Corn Belt and Upper Midwest, a key agricultural and wetland source region. Combing our seasonal results with prior fall values we find that wetlands are the largest regional methane source (32 %, 20 [16-23] Gg/d), while livestock (enteric/manure; 25 %, 15 [14-17] Gg/d) are the largest anthropogenic source. Natural gas/petroleum, waste/landfills, and coal mines collectively make up the remainder. Optimized fluxes improve model agreement with independent datasets within and beyond the study timeframe. Inversions reveal coherent and seasonally dependent spatial errors in the WetCHARTs ensemble mean wetland emissions, with an underestimate for the Prairie Pothole region but an overestimate for Great Lakes coastal wetlands. Wetland extent and emission temperature dependence have the largest influence on prediction accuracy; better representation of coupled soil temperature-hydrology effects is therefore needed. Our optimized regional livestock emissions agree well with the Gridded EPA estimates during spring (to within 7 %) but are g≈ 25 % higher during summer and winter. Spatial analysis further shows good top-down and bottom-up agreement for beef facilities (with mainly enteric emissions) but larger (g≈ 30 %) seasonal discrepancies for dairies and hog farms (with > 40 % manure emissions). Findings thus support bottom-up enteric emission estimates but suggest errors for manure; we propose that the latter reflects inadequate treatment of management factors including field application. Overall, our results confirm the importance of intensive animal agriculture for regional methane emissions, implying substantial mitigation opportunities through improved management.
Department
Department of Earth and Environmental Sciences
Original Publication Date
1-25-2021
Object Description
1 PDF file
DOI of published version
10.5194/acp-21-951-2021
Repository
UNI ScholarWorks, Rod Library, University of Northern Iowa
Copyright
©2021 by the Authors. CC BY license.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Language
en
File Format
application/pdf
Recommended Citation
Yu, Xueying; Millet, Dylan B.; Wells, Kelley C.; Henze, Daven K.; Cao, Hansen; Griffis, Timothy V.; Kort, Eric A.; Plant, Genevieve; Deventer, Malte J.; Kolka, Randall K.; Tyler Roman, D.; Davis, Kenneth J.; Desai, Ankur R.; Baier, Bianca C.; McKain, Kathryn; Czarnetzki, Alan C.; and Anthony Bloom, A., "Aircraft-Based Inversions Quantify The Importance Of Wetlands And Livestock For Upper Midwest Methane Emissions" (2021). Faculty Publications. 125.
https://scholarworks.uni.edu/facpub/125
Comments
First published in Atmospheric Chemistry and Physics, v.21, pp. 951-971 (2021), by the European Geosciences Union. DOI: 10.5194/acp-21-951-2021