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The global budget of atmospheric methanol: new constraints on secondary, oceanic, and terrestrial sources

Bates, Kelvin H. and Jacob, Daniel J. and Wang, Siyuan and Hornbrook, Rebecca S. and Apel, Eric C. and Kim, Michelle J. and Millet, Dylan B. and Wells, Kelley C. and Chen, Xin and Brewer, Jared F. and Ray, Eric A. and Commane, Róisín and Diskin, Glenn S. and Wofsy, Steven C. (2021) The global budget of atmospheric methanol: new constraints on secondary, oceanic, and terrestrial sources. Journal of Geophysical Research. Atmospheres, 126 (4). Art. No. e2020JD033439. ISSN 2169-897X.

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Methanol is the second‐most abundant organic gas in the remote atmosphere after methane, but its sources are poorly understood. Here, we report a global budget of methanol constrained by observations from the ATom aircraft campaign as implemented in the GEOS‐Chem global atmospheric chemistry model. ATom observations under background marine conditions can be fit in the model with a surface ocean methanol concentration of 61 nM and a methanol yield of 13% from the newly implemented CH₃O₂ + OH reaction. While terrestrial biogenic emissions dominate the global atmospheric methanol budget, secondary production from CH₃O₂ + OH and CH₃O₂ + CH₃O₂ accounts for 29% of the total methanol source, and makes up the majority of methanol in the background marine atmosphere sampled by ATom. Net emission from the ocean is comparatively minor, particularly because of rapid deposition from the marine boundary layer. Aged anthropogenic and pyrogenic plumes sampled in ATom featured large methanol enhancements to constrain the corresponding sources. Methanol enhancements in pyrogenic plumes did not decay with age, implying in‐plume secondary production. The atmospheric lifetime of methanol is only 5.3 days, reflecting losses of comparable magnitude from photooxidation and deposition. GEOS‐Chem model results indicate that methanol photochemistry contributes 5%, 4%, and 1.5% of the tropospheric burdens of formaldehyde, CO, and ozone, respectively, with particularly pronounced effects in the tropical upper troposphere. The CH₃O₂ + OH reaction has substantial impacts on radical budgets throughout the troposphere and should be included in global atmospheric chemistry models.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemATom data Atmospheric Tomography mission data
Bates, Kelvin H.0000-0001-7544-9580
Jacob, Daniel J.0000-0002-6373-3100
Wang, Siyuan0000-0002-8110-5714
Hornbrook, Rebecca S.0000-0002-6304-6554
Apel, Eric C.0000-0001-9421-818X
Kim, Michelle J.0000-0002-4922-4334
Millet, Dylan B.0000-0003-3076-125X
Wells, Kelley C.0000-0003-3025-6878
Chen, Xin0000-0002-0952-0008
Brewer, Jared F.0000-0003-2884-6203
Ray, Eric A.0000-0001-8727-9849
Commane, Róisín0000-0003-1373-1550
Diskin, Glenn S.0000-0002-3617-0269
Wofsy, Steven C.0000-0002-3133-2089
Additional Information:© 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. Issue Online: 22 February 2021; Version of Record online: 22 February 2021; Accepted manuscript online: 03 February 2021; Manuscript accepted: 14 January 2021; Manuscript revised: 18 December 2020; Manuscript received: 04 July 2020. This work was supported by the US NSF Atmospheric Chemistry Program, by the NASA Atmospheric Composition Modeling and Analysis Program, and by the US EPA Science to Achieve Results Program. We thank Bruce Daube and Kathryn McKain for their contribution to the collection of CO data on ATom. K. H. B. acknowledges additional support from the Harvard University Center for the Environment and the National Oceanic and Atmospheric Administration’s Climate and Global Change Fellowship programs. D. B. M., X. C., and K. C. W. acknowledge support from the NASA Atmospheric Composition Campaign Data Analysis and Modeling (ACCDAM) program (Grant no. NNX14AP89G). This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under Cooperative Agreement No. 1852977. All ATom data used in this study can be accessed via Data Availability Statement: Data from the NASA Atmospheric Tomography mission are available at
Funding AgencyGrant Number
Environmental Protection Agency (EPA)UNSPECIFIED
Harvard UniversityUNSPECIFIED
National Oceanic and Atmospheric Administration (NOAA)UNSPECIFIED
Subject Keywords:air‐sea exchange; atmospheric tomography; chemical transport modeling; methanol
Issue or Number:4
Record Number:CaltechAUTHORS:20210208-160723986
Persistent URL:
Official Citation:Bates, K. H., Jacob, D. J., Wang, S., Hornbrook, R. S., Apel, E. C., Kim, M. J., et al. (2021). The global budget of atmospheric methanol: New constraints on secondary, oceanic, and terrestrial sources. Journal of Geophysical Research: Atmospheres, 126, e2020JD033439.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107963
Deposited By: George Porter
Deposited On:09 Feb 2021 15:39
Last Modified:22 Feb 2021 20:53

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