Publication Date:
2014-09-12
Description:
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, 7-10). 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Patra, P K -- Krol, M C -- Montzka, S A -- Arnold, T -- Atlas, E 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 -- Muhle, J -- O'Doherty, S -- Prinn, R G -- Steele, L P -- Takigawa, M -- Wang, H J -- Weiss, R F -- Wofsy, S C -- Young, D -- England -- Nature. 2014 Sep 11;513(7517):219-23. doi: 10.1038/nature13721.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Environmental Geochemical Cycle Research, JAMSTEC, Yokohama 236 0001, Japan [2] CAOS, Graduate School of Studies, Tohoku University, Sendai 980 8578, Japan. ; Wageningen University, Droevendaalsesteeg 3a, 6708 PB, The Netherlands. ; National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, Boulder, Colorado 80305, USA. ; Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA. ; The Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida 33149, USA. ; Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA. ; National Center for Atmospheric Research (NCAR), Boulder, Colorado 80301, USA. ; School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138, USA. ; Centre for Australian Weather and Climate Research, Commonwealth Scientific and Industrial Research Organisation (CSIRO) Oceans and Atmosphere Flagship, Aspendale, Victoria 3195, Australia. ; 1] Department of Environmental Geochemical Cycle Research, JAMSTEC, Yokohama 236 0001, Japan [2] National Institute of Polar Research, 10-3, Midoricho, Tachikawa, Tokyo 190-8518, Japan. ; 1] National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, Boulder, Colorado 80305, USA [2] CIRES, University of Colorado, Boulder, Colorado 80309, USA. ; Department of Environmental Geochemical Cycle Research, JAMSTEC, Yokohama 236 0001, Japan. ; School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, UK. ; Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. ; School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25209800" target="_blank"〉PubMed〈/a〉
Keywords:
Air Pollutants/chemistry
;
Atmosphere/*chemistry
;
Chloroform/chemistry
;
Computer Simulation
;
Hydroxyl Radical/*chemistry
;
*Models, Theoretical
;
Nitrogen Oxides/chemistry
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
Permalink
