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Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations

Wolfe, Glenn M. and Nicely, Julie M. and St. Clair, Jason M. and Hanisco, Thomas F. and Liao, Jin and Oman, Luke D. and Brune, William B. and Miller, David and Thames, Alexander and González Abad, Gonzalo and Ryerson, Thomas B. and Thompson, Chelsea R. and Peischl, Jeff and McKain, Kathryn and Sweeney, Colm and Wennberg, Paul O. and Kim, Michelle and Crounse, John D. and Hall, Samuel R. and Ullmann, Kirk and Diskin, Glenn and Bui, Paul and Chang, Cecilia and Dean-Day, Jonathan (2019) Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations. Proceedings of the National Academy of Sciences of the United States of America, 116 (23). pp. 11171-11180. ISSN 0027-8424. PMCID PMC6561255; PMC6601245. doi:10.1073/pnas.1821661116.

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The hydroxyl radical (OH) fuels tropospheric ozone production and governs the lifetime of methane and many other gases. Existing methods to quantify global OH are limited to annual and global-to-hemispheric averages. Finer resolution is essential for isolating model deficiencies and building process-level understanding. In situ observations from the Atmospheric Tomography (ATom) mission demonstrate that remote tropospheric OH is tightly coupled to the production and loss of formaldehyde (HCHO), a major hydrocarbon oxidation product. Synthesis of this relationship with satellite-based HCHO retrievals and model-derived HCHO loss frequencies yields a map of total-column OH abundance throughout the remote troposphere (up to 70% of tropospheric mass) over the first two ATom missions (August 2016 and February 2017). This dataset offers unique insights on near-global oxidizing capacity. OH exhibits significant seasonality within individual hemispheres, but the domain mean concentration is nearly identical for both seasons (1.03 ± 0.25 × 10^6 cm^(−3)), and the biseasonal average North/South Hemisphere ratio is 0.89 ± 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10-fold OH depression in the Tropical West Pacific and enhancements in the East Pacific and South Atlantic. This method is complementary to budget-based global OH constraints and can help elucidate the spatial and temporal variability of OH production and methane loss.

Item Type:Article
Related URLs:
URLURL TypeDescription Information ItemData CentralArticle CentralCorrection
Wolfe, Glenn M.0000-0001-6586-4043
Nicely, Julie M.0000-0003-4828-0032
St. Clair, Jason M.0000-0002-9367-5749
Hanisco, Thomas F.0000-0001-9434-8507
Oman, Luke D.0000-0002-5487-2598
González Abad, Gonzalo0000-0002-8090-6480
Ryerson, Thomas B.0000-0003-2800-7581
Thompson, Chelsea R.0000-0002-7332-9945
Peischl, Jeff0000-0002-9320-7101
Sweeney, Colm0000-0001-9568-0050
Wennberg, Paul O.0000-0002-6126-3854
Kim, Michelle0000-0002-4922-4334
Crounse, John D.0000-0001-5443-729X
Hall, Samuel R.0000-0002-2060-7112
Ullmann, Kirk0000-0002-4724-9634
Diskin, Glenn0000-0002-3617-0269
Bui, Paul0000-0001-9189-0405
Dean-Day, Jonathan0000-0003-2621-5774
Additional Information:© 2019 National Academy of Sciences. Published under the PNAS license. Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved April 22, 2019 (received for review December 19, 2018). We thank all of the NASA pilots, crew, logistical personnel, and science leadership who facilitated the ATom mission. We thank Clare Flynn for assembling the merged dataset used to constrain 0-D box model simulations, and we also thank the many scientists contributing observations to this dataset. We thank Can Li, Joanna Joiner, Arlene Fiore, and Colleen Baublitz for helpful discussions and feedback. This work was supported by the NASA ATom Earth Venture Suborbital-2 Program. The NASA Goddard Space Flight Center (GSFC) team acknowledges support from Atmospheric Composition Campaign Data Analysis and Modeling Grant NNX14AP48G, the NASA Upper Atmospheric Research Program, and the NASA Tropospheric Composition Program. J.M.N. was also supported by an appointment to the NASA Postdoctoral Program at the NASA GSFC, administered by the Universities Space Research Association under contract. OMI HCHO columns were developed with NASA support from Atmospheric Composition Modeling and Analysis Grant NNX17AH47G and the Aura Science Team. The Modern-Era Retrospective Analysis for Research and Applications 2 GMI simulation was supported by the NASA Modeling, Analysis, and Prediction Program and computational resources from the NASA Center for Climate Simulation. M.K. was funded by NSF Atmospheric and Geospace Sciences Postdoctoral Research Fellowship 1524860. Finally, we thank three anonymous reviewers for their expert critique of the manuscript. Author contributions: G.M.W. and J.M.N. designed research; G.M.W., J.M.N., T.F.H., L.D.O., W.B.B., D.M., A.T., G.G.A., T.B.R., C.R.T., J.P., K.M., C.S., P.O.W., M.K., J.D.C., S.R.H., K.U., G.D., P.B., and C.C. performed research; G.M.W., J.M.N., J.M.S.C., J.L., and J.D.-D. analyzed data; G.M.W. wrote the paper; G.M.W., J.M.S.C., T.F.H., W.B.B., D.M., A.T., T.B.R., C.R.T., J.P., K.M., C.S., P.O.W., M.K., J.D.C., S.R.H., K.U., G.D., P.B., C.C., and J.D.-D. contributed to ATom observations; L.D.O. provided GMI model output; and G.G.A. provided OMI retrievals. The authors declare no conflict of interest. This article is a PNAS Direct Submission. Data deposition: The data reported in this paper have been deposited in the Oak Ridge National Laboratory ( This article contains supporting information online at
Errata:The authors note that the author name Kathryn McCain should instead appear as Kathryn McKain. The corrected author line appears below. The online version has been corrected.
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
Subject Keywords:hydroxyl; formaldehyde; ATom; OMI; troposphere
Issue or Number:23
PubMed Central ID:PMC6561255; PMC6601245
Record Number:CaltechAUTHORS:20190521-075102186
Persistent URL:
Official Citation:Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations. Glenn M. Wolfe, Julie M. Nicely, Jason M. St. Clair, Thomas F. Hanisco, JinLiao, Luke D. Oman, William B. Brune, David Miller, Alexander Thames, Gonzalo González Abad, Thomas B. Ryerson, Chelsea R. Thompson, JeffPeischl, Kathryn McCain, Colm Sweeney, Paul O. Wennberg, MichelleKim, John D. Crounse, Samuel R. Hall, Kirk Ullmann, Glenn Diskin, PaulBui, Cecilia Chang, Jonathan Dean-Day. Proceedings of the National Academy of Sciences Jun 2019, 116 (23) 11171-11180; DOI:10.1073/pnas.1821661116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95622
Deposited By: Tony Diaz
Deposited On:21 May 2019 18:19
Last Modified:16 Feb 2022 23:44

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