The oxidizing capacity of the global atmosphere is largely determined by hydroxyl (OH) radicals and is diagnosed by analyzing methyl chloroform (CH3CCl3) measurements. Previously, large year-to-year changes in global mean OH concentrations have been inferred from such measurements, suggesting that the atmospheric oxidizing capacity is sensitive to perturbations by widespread air pollution and natural influences. We show how the interannual variability in OH has been more precisely estimated from CH3CCl3 measurements since 1998, when atmospheric gradients of CH3CCl3 had diminished as a result of the Montreal Protocol. We infer a small interannual OH variability as a result, indicating that global OH is generally well buffered against perturbations. This small variability is consistent with measurements of methane and other trace gases oxidized primarily by OH, as well as global photochemical model calculations.
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References and Notes

Levy H., Normal atmosphere: Large radical and formaldehyde concentrations predicted. Science 173, 141 (1971).
Logan J. A., Prather M. J., Wofsy S. C., McElroy M. B., Tropospheric chemistry: A global perspective. J. Geophys. Res. 86, 7210 (1981).
Spivakovsky C. M., et al., Three-dimensional climatological distribution of tropospheric OH: Update and evaluation. J. Geophys. Res. 105, 8931 (2000).
P. Forster et al., in Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S. Solomon et al., Eds. (Cambridge Univ. Press, Cambridge, 2007), pp. 129–234.
Wang Y., Jacob D. J., Anthropogenic forcing on tropospheric ozone and OH since preindustrial times. J. Geophys. Res. 103, 31123 (1998).
D. Ehhalt et al., in Climate Change 2001, The Scientific Basis, J. T. Houghton et al., Eds. (Cambridge Univ. Press, New York, 2001), pp. 239–287.
Lelieveld J., Dentener F. J., Peters W., Krol M. C., On the role of hydroxyl radicals in the self-cleansing capacity of the troposphere. Atmos. Chem. Phys. 4, 2337 (2004).
Lelieveld J., et al., Atmospheric oxidation capacity sustained by a tropical forest. Nature 452, 737 (2008).
Weinstock B., Niki H., Carbon monoxide balance in nature. Science 176, 290 (1972).
Singh H. B., Preliminary estimation of average tropospheric HO concentrations in the northern and southern hemispheres. Geophys. Res. Lett. 4, 453 (1977).
Lovelock J. E., Methyl chloroform in the troposphere as an indicator of OH radical abundance. Nature 267, 32 (1977).
Brenninkmeijer C. A. M., et al., Interhemispheric asymmetry in OH abundance inferred from measurements of atmospheric 14CO. Nature 356, 50 (1992).
Mak J. E., Brenninkmeijer C. A. M., Manning M. R., Evidence for a missing carbon monoxide sink based on tropospheric measurements of 14CO. Geophys. Res. Lett. 19, 1467 (1992).
Montzka S. A., et al., New observational constraints for atmospheric hydroxyl on global and hemispheric scales. Science 288, 500 (2000).
Jöckel P., Brenninkmeijer C. A. M., Lawrence M. G., Jeuken A. B. M., van Velthoven P. F. J., Evaluation of stratosphere-troposphere exchange and the hydroxyl radical distribution in three-dimensional global atmospheric models using observations of cosmogenic 14CO. J. Geophys. Res. 107, 4446 (2002).
Bousquet P., Hauglustaine D. A., Peylin P., Carouge C., Ciais P., Two decades of OH variability as inferred by an inversion of atmospheric transport and chemistry of methyl chloroform. Atmos. Chem. Phys. 5, 2635 (2005).
Prinn R. G., et al., Evidence for variability of atmospheric hydroxyl radicals over the past quarter century. Geophys. Res. Lett. 32, L07809 (2005).
Krol M. C., et al., What can 14CO measurements tell us about OH? Atmos. Chem. Phys. 8, 5033 (2008).
Manning M. R., Lowe D. C., Moss R. C., Bodeker G. E., Allan W., Short-term variations in the oxidizing power of the atmosphere. Nature 436, 1001 (2005).
Lelieveld J., et al., New directions: Watching over tropospheric hydroxyl (OH). Atmos. Environ. 40, 5741 (2006).
Dentener F., et al., Interannual variability and trend of CH4 lifetime as a measure for OH changes in the 1979–1993 time period. J. Geophys. Res. 108, 4442 (2003).
Duncan B., Logan J., Model analysis of the factors regulating the trends and variability of carbon monoxide between 1988 and 1997. Atmos. Chem. Phys. 8, 7389 (2008).
Dalsøren S. B., Isaksen I. S. A., CTM study of changes in tropospheric hydroxyl distribution 1990–2001 and its impact on methane. Geophys. Res. Lett. 33, L23811 (2006).
See supporting material on Science Online.
Rigby M., et al., Renewed growth of atmospheric methane. Geophys. Res. Lett. 35, L22805 (2008).
Krol M., Lelieveld J., Can the variability in tropospheric OH be deduced from measurements of 1,1,1-trichloroethane (methyl chloroform)? J. Geophys. Res. 108, 4125 (2003).
Dlugokencky E. J., et al., Observational constraints on recent increases in the atmospheric CH4 burden. Geophys. Res. Lett. 36, L18803 (2009).
van der Werf G. R., et al., Interannual variability in global biomass burning emissions from 1997 to 2004. Atmos. Chem. Phys. 6, 3423 (2006).
Walter B. P., Heimann M., Matthews E., Modeling modern methane emissions from natural wetlands 1. Model description and results. J. Geophys. Res. 106, 34189 (2001).
Jöckel P., et al., The atmospheric chemistry general circulation model ECHAM5/MESSy1: Consistent simulation of ozone from the surface to the mesosphere. Atmos. Chem. Phys. 6, 5067 (2006).

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Published In

Volume 331Issue 60137 January 2011
Pages: 67 - 69
PubMed: 21212353


Received: 10 September 2010
Accepted: 22 November 2010


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We thank C. Siso, B. Miller, L. Miller, D. Mondeel, L. Bruhwiler, P. Novelli, B. Weatherhead, J. W. Elkins, J. H. Butler, station personnel involved with sampling flasks, C. M. Spivakovsky, R. G. Prinn, and other AGAGE scientists, P. Bergamaschi, and J.-F. Meirink. Supported in part by the Atmospheric Composition and Climate Program of NOAA’s Climate Program Office and by the Stichting Nationale Computerfaciliteiten (National Computing Facilities Foundation).



S. A. Montzka* [email protected]
NOAA Earth System Research Laboratory, Boulder, CO 80305, USA.
M. Krol
Institute for Marine and Atmospheric Research Utrecht, University of Utrecht, 3584 CC Utrecht, Netherlands.
Meteorology and Air Quality Group, Wageningen University, 6708 PB Wageningen, Netherlands.
E. Dlugokencky
NOAA Earth System Research Laboratory, Boulder, CO 80305, USA.
B. Hall
NOAA Earth System Research Laboratory, Boulder, CO 80305, USA.
P. Jöckel
Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, D-55128 Mainz, Germany.
J. Lelieveld
Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, D-55128 Mainz, Germany.
Cyprus Institute, Nicosia 1645, Cyprus.


*To whom correspondence should be addressed. E-mail: [email protected]
Present address: Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, D-82234 Wessling, Germany.

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Volume 331|Issue 6013
7 January 2011
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Received:10 September 2010
Accepted:22 November 2010
Published in print:7 January 2011
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