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 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 219-223 |
| Number of pages | 5 |
| Journal | Nature |
| Volume | 513 |
| Issue number | 7517 |
| DOIs | |
| State | Published - Sep 11 2014 |
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Observational evidence for interhemispheric hydroxyl-radical parity. / Patra, P. K.; Krol, M. C.; Montzka, S. A.; Arnold, T.; Atlas, Elliot L; Lintner, B. R.; Stephens, B. B.; Xiang, B.; Elkins, J. W.; Fraser, P. J.; Ghosh, A.; Hintsa, E. J.; Hurst, D. F.; Ishijima, K.; Krummel, P. B.; Miller, B. R.; Miyazaki, K.; Moore, F. L.; Mühle, J.; O'Doherty, S.; Prinn, R. G.; Steele, L. P.; Takigawa, M.; Wang, H. J.; Weiss, R. F.; Wofsy, S. C.; Young, D.
In: Nature, Vol. 513, No. 7517, 11.09.2014, p. 219-223.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Observational evidence for interhemispheric hydroxyl-radical parity
AU - Patra, P. K.
AU - Krol, M. C.
AU - Montzka, S. A.
AU - Arnold, T.
AU - Atlas, Elliot L
AU - Lintner, B. R.
AU - Stephens, B. B.
AU - Xiang, B.
AU - Elkins, J. W.
AU - Fraser, P. J.
AU - Ghosh, A.
AU - Hintsa, E. J.
AU - Hurst, D. F.
AU - Ishijima, K.
AU - Krummel, P. B.
AU - Miller, B. R.
AU - Miyazaki, K.
AU - Moore, F. L.
AU - Mühle, J.
AU - O'Doherty, S.
AU - Prinn, R. G.
AU - Steele, L. P.
AU - Takigawa, M.
AU - Wang, H. J.
AU - Weiss, R. F.
AU - Wofsy, S. C.
AU - Young, D.
PY - 2014/9/11
Y1 - 2014/9/11
N2 - 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.
AB - 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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U2 - 10.1038/nature13721
DO - 10.1038/nature13721
M3 - Article
C2 - 25209800
AN - SCOPUS:84907261872
VL - 513
SP - 219
EP - 223
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7517
ER -