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Observational evidence for interhemispheric hydroxyl-radical parity

Patra, P. K. ; Krol, M. C. ; Montzka, S. A. ; Arnold, T. LU orcid ; Atlas, E. L. ; Lintner, B. R. ; Stephens, B. B. ; Xiang, B. ; Elkins, J. W. and Fraser, P. J. , et al. (2014) In Nature 513(7517). p.219-223
Abstract

The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane. It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4, 7,8,9,10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004-2011 the model predicts an annual mean NH-SH gradient of... (More)

The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane. It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4, 7,8,9,10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004-2011 the model predicts an annual mean NH-SH gradient of methyl chloroform that is a tight linear function of the modelled NH/SH ratio in annual mean OH. We estimate a NH/SH OH ratio of 0.97 ± 0.12 during this time period by optimizing global total emissions and mean OH abundance to fit methyl chloroform data from two surface-measurement networks and aircraft campaigns. Our findings suggest that top-down emission estimates of reactive species such as nitrogen oxides in key emitting countries in the NH that are based on a NH/SH OH ratio larger than 1 may be overestimated.

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publishing date
type
Contribution to journal
publication status
published
in
Nature
volume
513
issue
7517
pages
5 pages
publisher
Nature Publishing Group
external identifiers
  • pmid:25209800
  • scopus:84907261872
ISSN
0028-0836
DOI
10.1038/nature13721
language
English
LU publication?
no
additional info
Publisher Copyright: ©2014 Macmillan Publishers Limited. All rights reserved.
id
c9bd9662-e06b-4d45-90b5-cf00fdfef51c
date added to LUP
2024-10-24 18:29:08
date last changed
2025-06-06 14:18:55
@article{c9bd9662-e06b-4d45-90b5-cf00fdfef51c,
  abstract     = {{<p>The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane. It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4, 7,8,9,10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004-2011 the model predicts an annual mean NH-SH gradient of methyl chloroform that is a tight linear function of the modelled NH/SH ratio in annual mean OH. We estimate a NH/SH OH ratio of 0.97 ± 0.12 during this time period by optimizing global total emissions and mean OH abundance to fit methyl chloroform data from two surface-measurement networks and aircraft campaigns. Our findings suggest that top-down emission estimates of reactive species such as nitrogen oxides in key emitting countries in the NH that are based on a NH/SH OH ratio larger than 1 may be overestimated.</p>}},
  author       = {{Patra, P. K. and Krol, M. C. and Montzka, S. A. and Arnold, T. and Atlas, E. L. and Lintner, B. R. and Stephens, B. B. and Xiang, B. and Elkins, J. W. and Fraser, P. J. and Ghosh, A. and Hintsa, E. J. and Hurst, D. F. and Ishijima, K. and Krummel, P. B. and Miller, B. R. and Miyazaki, K. and Moore, F. L. and Mühle, J. and O'Doherty, S. and Prinn, R. G. and Steele, L. P. and Takigawa, M. and Wang, H. J. and Weiss, R. F. and Wofsy, S. C. and Young, D.}},
  issn         = {{0028-0836}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{7517}},
  pages        = {{219--223}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature}},
  title        = {{Observational evidence for interhemispheric hydroxyl-radical parity}},
  url          = {{http://dx.doi.org/10.1038/nature13721}},
  doi          = {{10.1038/nature13721}},
  volume       = {{513}},
  year         = {{2014}},
}