Speciation of OH reactivity above the canopy of an isoprene-dominated forest
- Creators
- Kaiser, J.
- Skog, K. M.
- Baumann, K.
- Bertman, S. B.
- Brown, S. B.
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Brune, W. H.
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Crounse, J. D.
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de Gouw, J. A.
- Edgerton, E. S.
- Brown, P. A.
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Goldstein, A. H.
- Koss, A.
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Misztal, P. K.
- Nguyen, T. B.
- Olson, K. F.
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St. Clair, J. M.
- Teng, A. P.
- Toma, S.
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Wennberg, P. O.
- Wild, R. J.
- Zhang, L.
- Keutsch, F. N.
Abstract
Measurements of OH reactivity, the inverse lifetime of the OH radical, can provide a top–down estimate of the total amount of reactive carbon in an air mass. Using a comprehensive measurement suite, we examine the measured and modeled OH reactivity above an isoprene-dominated forest in the southeast United States during the 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign. Measured and modeled species account for the vast majority of average daytime reactivity (80–95 %) and a smaller portion of nighttime and early morning reactivity (68–80 %). The largest contribution to total reactivity consistently comes from primary biogenic emissions, with isoprene contributing ∼ 60 % in the afternoon, and ∼ 30–40 % at night and monoterpenes contributing ∼ 15–25 % at night. By comparing total reactivity to the reactivity stemming from isoprene alone, we find that ∼ 20 % of the discrepancy is temporally related to isoprene reactivity, and an additional constant ∼ 1 s^(−1) offset accounts for the remaining portion. The model typically overestimates measured OVOC concentrations, indicating that unmeasured oxidation products are unlikely to influence measured OH reactivity. Instead, we suggest that unmeasured primary emissions may influence the OH reactivity at this site.
Additional Information
© 2016 Author(s). © Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 11 Dec 2015. Published in Atmos. Chem. Phys. Discuss.: 18 Jan 2016. Revised: 12 Jul 2016. Accepted: 12 Jul 2016. Published: 28 Jul 2016. The authors would like to acknowledge contribution from all members of the SOAS science team. Funding was provided by US EPA "Science to Achieve Results (STAR) program" Grant 83540601. A. H. Goldstein and P. K. Misztal acknowledge support from EPA STAR Grant R835407. This research has not been subjected to any EPA review and therefore does not necessarily reflect the views of the Agency, and no official endorsement should be inferred. Additional funding was provided by NSF-grant AGS-1247421 and 1628530. J. Kaiser acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program – Grant NNX14AK97H. Edited by: N. L. Ng. Reviewed by: two anonymous referees.Attached Files
Published - acp-16-9349-2016.pdf
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Additional details
- Eprint ID
- 70955
- Resolver ID
- CaltechAUTHORS:20161007-142943299
- Environmental Protection Agency (EPA)
- 83540601
- Environmental Protection Agency (EPA)
- R835407
- NSF
- AGS-1247421
- NSF
- AGS-1628530
- NASA Earth and Space Science Fellowship
- NNX14AK97H
- Created
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2016-10-12Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences