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Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements

Guo, Hao and Flynn, Clare M. and Prather, Michael J. and Strode, Sarah A. and Steenrod, Stephen D. and Emmons, Louisa and Lacey, Forrest and Lamarque, Jean-Francois and Fiore, Arlene M. and Correa, Gus and Murray, Lee T. and Wolfe, Glenn M. and St. Clair, Jason M. and Kim, Michelle and Crounse, John and Diskin, Glenn and DiGangi, Joshua and Daube, Bruce C. and Commane, Roisin and McKain, Kathryn and Peischl, Jeff and Ryerson, Thomas B. and Thompson, Chelsea and Hanisco, Thomas F. and Blake, Donald and Blake, Nicola J. and Apel, Eric C. and Hornbrook, Rebecca S. and Elkins, James W. and Hintsa, Eric J. and Moore, Fred L. and Wofsy, Steven (2021) Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements. Atmospheric Chemistry and Physics, 21 (18). pp. 13729-13746. ISSN 1680-7324. doi:10.5194/acp-21-13729-2021.

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The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10 s (2 km) merged and gap-filled observations of the key reactive species driving the chemical budgets of O₃ and CH₄ (O₃, CH₄, CO, H₂O, HCHO, H₂O₂, CH₃OOH, C₂H6, higher alkanes, alkenes, aromatics, NO_x, HNO₃, HNO₄, peroxyacetyl nitrate, other organic nitrates), consisting of 146 494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O₃ and CH₄ photochemical tendencies from this modeling data stream for ATom 1. We find that 80 %–90 % of the total reactivity lies in the top 50 % of the parcels and 25 %–35 % in the top 10 %, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. In other words, accurate simulation of the least reactive 50 % of the troposphere is unimportant for global budgets. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100 km) differ only slightly from the 2 km ATom data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find excellent agreement with the loss of O₃ and CH₄ but sharp disagreement with production of O₃. The models sharply underestimate O₃ production below 4 km in both Pacific and Atlantic basins, and this can be traced to lower NO_x levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-to-what-matters, set of metrics for model evaluation.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Guo, Hao0000-0001-5082-273X
Flynn, Clare M.0000-0002-7158-1119
Prather, Michael J.0000-0002-9442-8109
Strode, Sarah A.0000-0002-8103-1663
Steenrod, Stephen D.0000-0003-0935-7172
Emmons, Louisa0000-0003-2325-6212
Lacey, Forrest0000-0003-4578-8375
Lamarque, Jean-Francois0000-0002-4225-5074
Fiore, Arlene M.0000-0003-0221-2122
Correa, Gus0000-0002-0098-7322
Murray, Lee T.0000-0002-3447-3952
Wolfe, Glenn M.0000-0001-6586-4043
St. Clair, Jason M.0000-0002-9367-5749
Kim, Michelle0000-0002-4922-4334
Crounse, John0000-0001-5443-729X
Diskin, Glenn0000-0002-3617-0269
DiGangi, Joshua0000-0002-6764-8624
Commane, Roisin0000-0003-1373-1550
McKain, Kathryn0000-0002-8323-5758
Peischl, Jeff0000-0002-9320-7101
Ryerson, Thomas B.0000-0003-2800-7581
Thompson, Chelsea0000-0002-7332-9945
Hanisco, Thomas F.0000-0001-9434-8507
Blake, Donald0000-0002-8283-5014
Apel, Eric C.0000-0001-9421-818X
Hornbrook, Rebecca S.0000-0002-6304-6554
Elkins, James W.0000-0003-4701-3100
Hintsa, Eric J.0000-0002-5289-630X
Moore, Fred L.0000-0002-8461-2535
Wofsy, Steven0000-0002-3990-6737
Additional Information:© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 13 May 2021 – Discussion started: 19 May 2021 – Revised: 20 Aug 2021 – Accepted: 24 Aug 2021 – Published: 16 Sep 2021. The authors are indebted to the entire ATom Science Team including the managers, pilots and crew, who made this mission possible. Many other scientists not on the author list enabled the measurements and model results used here. Primary funding of the preparation of this paper at UC Irvine was through NASA grants NNX15AG57A and 80NSSC21K1454. The Atmospheric Tomography Mission (ATom) was supported by the National Aeronautics and Space Administration's Earth System Science Pathfinder Venture-Class Science Investigations: Earth Venture Suborbital-2. Primary funding of the preparation of this paper at UC Irvine was through NASA (grant nos. NNX15AG57A and 80NSSC21K1454). Author contributions. HG, CMF, SCW and MJP designed the research and performed the data analysis. SAS, SDS, LE, FL, JL, AMF, GC, LTM and GW contributed original atmospheric chemistry model results. GW, MK, JC, GD, JD, BCD, RC, KM, JP, TBR, CT, TFH, DB, NJB, ECA, RSH, JE, EH and FM contributed original atmospheric observations. HG, CMF and MJP wrote the paper. The contact author has declared that neither they nor their co-authors have any competing interests. This paper was edited by Neil Harris and reviewed by two anonymous referees.
Funding AgencyGrant Number
Issue or Number:18
Record Number:CaltechAUTHORS:20211008-224638198
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Official Citation:Guo, H., Flynn, C. M., Prather, M. J., Strode, S. A., Steenrod, S. D., Emmons, L., Lacey, F., Lamarque, J.-F., Fiore, A. M., Correa, G., Murray, L. T., Wolfe, G. M., St. Clair, J. M., Kim, M., Crounse, J., Diskin, G., DiGangi, J., Daube, B. C., Commane, R., McKain, K., Peischl, J., Ryerson, T. B., Thompson, C., Hanisco, T. F., Blake, D., Blake, N. J., Apel, E. C., Hornbrook, R. S., Elkins, J. W., Hintsa, E. J., Moore, F. L., and Wofsy, S.: Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements , Atmos. Chem. Phys., 21, 13729–13746,, 2021.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111341
Deposited By: George Porter
Deposited On:11 Oct 2021 14:35
Last Modified:11 Oct 2021 14:35

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