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Assessing urban methane emissions using column-observing portable Fourier transform infrared (FTIR) spectrometers and a novel Bayesian inversion framework

Jones, Taylor S. and Franklin, Jonathan E. and Chen, Jia and Dietrich, Florian and Hajny, Kristian D. and Paetzold, Johannes C. and Wenzel, Adrian and Gately, Conor and Gottlieb, Elaine and Parker, Harrison and Dubey, Manvendra and Hase, Frank and Shepson, Paul B. and Mielke, Levi H. and Wofsy, Steven C. (2021) Assessing urban methane emissions using column-observing portable Fourier transform infrared (FTIR) spectrometers and a novel Bayesian inversion framework. Atmospheric Chemistry and Physics, 21 (17). pp. 13131-13147. ISSN 1680-7324. doi:10.5194/acp-21-13131-2021. https://resolver.caltech.edu/CaltechAUTHORS:20211001-205553178

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Abstract

Cities represent a large and concentrated portion of global greenhouse gas emissions, including methane. Quantifying methane emissions from urban areas is difficult, and inventories made using bottom-up accounting methods often differ greatly from top-down estimates generated from atmospheric observations. Emissions from leaks in natural gas infrastructure are difficult to predict and are therefore poorly constrained in bottom-up inventories. Natural gas infrastructure leaks and emissions from end uses can be spread throughout the city, and this diffuse source can represent a significant fraction of a city's total emissions. We investigated diffuse methane emissions of the city of Indianapolis, USA, during a field campaign in May 2016. A network of five portable solar-tracking Fourier transform infrared (FTIR) spectrometers was deployed throughout the city. These instruments measure the mole fraction of methane in a total column of air, giving them sensitivity to larger areas of the city than in situ sensors at the surface. We present an innovative inversion method to link these total column concentrations to surface fluxes. This method combines a Lagrangian transport model with a Bayesian inversion framework to estimate surface emissions and their uncertainties, together with determining the concentrations of methane in the air flowing into the city. Variations exceeding 10 ppb were observed in the inflowing air on a typical day, which is somewhat larger than the enhancements due to urban emissions (<5 ppb downwind of the city). We found diffuse methane emissions of 73(±22) mol s⁻¹, which is about 50 % of the urban total and 68 % higher than estimated from bottom-up methods, although it is somewhat smaller than estimates from studies using tower and aircraft observations. The measurement and model techniques developed here address many of the challenges present when quantifying urban greenhouse gas emissions and will help in the design of future measurement schemes in other cities.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.5194/acp-21-13131-2021DOIArticle
https://doi.org/10.5194/acp-21-13131-2021-supplementDOISupplement
https://doi.org/10.7910/DVN/JWL4PKDOIData
ORCID:
AuthorORCID
Jones, Taylor S.0000-0003-2077-6757
Chen, Jia0000-0002-6350-6610
Dietrich, Florian0000-0002-3069-9946
Hajny, Kristian D.0000-0003-3249-7157
Wenzel, Adrian0000-0001-6016-6174
Gately, Conor0000-0002-4060-4947
Parker, Harrison0000-0002-0041-2764
Dubey, Manvendra0000-0002-3492-790X
Shepson, Paul B.0000-0002-1726-3291b
Wofsy, Steven C.0000-0002-3133-2089
Additional Information:© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 11 December 2020 – Discussion started: 4 January 2021; Revised: 11 July 2021 – Accepted: 25 July 2021 – Published: 6 September 2021. The authors would like to thank the University of Indianapolis for hosting this experiment and providing vital ground support. We would also like to thank Ludwig Heinle, Bruce Daube, John Budney, and Cody Floerchinger for their assistance with technical support, experimental design, and field measurements. We would like to thank the Environment Defense Fund for their financial support of this work. Jia Chen, Florian Dietrich, Adrian Wenzel, and Johannes C. Paetzold acknowledge financial support from the Deutsche Forschungsgemeinschaft (CH 1792/2-1; INST 95/1544) and Technical University of Munich–Institute for Advanced Study, funded by the German Excellence Initiative and the European Union Seventh Framework Program under grant agreement number 291763. Harrison Parker and Manvendra Dubey are grateful for support from LANL's LDRD, NASA's Carbon Monitoring, and UCOPs dairy methane emission projects. This research has been supported by the Environmental Defense Fund, the Deutsche Forschungsgemeinschaft (grant nos. CH 1792/2-1 and INST 95/1544), and the Technical University of Munich–Institute for Advanced Study, funded by the German Excellence Initiative and the European Union Seventh Framework Program under grant agreement number 291763. Code and data availability: The data and inversion code used in this study are available from the Harvard Dataverse: https://doi.org/10.7910/DVN/JWL4PK (Jones et al., 2020). Supplement: The supplement related to this article is available online at: https://doi.org/10.5194/acp-21-13131-2021-supplement. Author contributions: TJ, JF, JC, and SW designed the measurement campaign. TJ, JF, JC, HP, and MD performed the measurements. KH and PS provided and analyzed aircraft data. EG processed campaign data. TJ, JC, FD, and CG designed the inversion framework. All authors contributed to writing the paper. The authors declare that they have no conflict of interest. Review statement: This paper was edited by Jerome Brioude and reviewed by two anonymous referees.
Funders:
Funding AgencyGrant Number
Environment Defense FundUNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)CH 1792/2-1
Deutsche Forschungsgemeinschaft (DFG)INST 95/1544
Technical University of MunichUNSPECIFIED
European Research Council (ERC)291763
Issue or Number:17
DOI:10.5194/acp-21-13131-2021
Record Number:CaltechAUTHORS:20211001-205553178
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20211001-205553178
Official Citation:Jones, T. S., Franklin, J. E., Chen, J., Dietrich, F., Hajny, K. D., Paetzold, J. C., Wenzel, A., Gately, C., Gottlieb, E., Parker, H., Dubey, M., Hase, F., Shepson, P. B., Mielke, L. H., and Wofsy, S. C.: Assessing urban methane emissions using column-observing portable Fourier transform infrared (FTIR) spectrometers and a novel Bayesian inversion framework, Atmos. Chem. Phys., 21, 13131–13147, https://doi.org/10.5194/acp-21-13131-2021, 2021
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111159
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Oct 2021 17:54
Last Modified:04 Oct 2021 17:54

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