Articles | Volume 13, issue 6
Atmos. Chem. Phys., 13, 3063–3085, 2013

Special issue: The Modular Earth Submodel System (MESSy) (ACP/GMD inter-journal...

Special issue: The Atmospheric Chemistry and Climate Model Intercomparison...

Atmos. Chem. Phys., 13, 3063–3085, 2013

Research article 15 Mar 2013

Research article | 15 Mar 2013

Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

D. S. Stevenson1, P. J. Young2,3,*, V. Naik4, J.-F. Lamarque5, D. T. Shindell6, A. Voulgarakis7, R. B. Skeie8, S. B. Dalsoren8, G. Myhre8, T. K. Berntsen8, G. A. Folberth9, S. T. Rumbold9, W. J. Collins9,**, I. A. MacKenzie1, R. M. Doherty1, G. Zeng10, T. P. C. van Noije11, A. Strunk11, D. Bergmann12, P. Cameron-Smith12, D. A. Plummer13, S. A. Strode14,15, L. Horowitz16, Y. H. Lee6, S. Szopa17, K. Sudo18, T. Nagashima19, B. Josse20, I. Cionni21, M. Righi22, V. Eyring22, A. Conley5, K. W. Bowman23, O. Wild24, and A. Archibald25 D. S. Stevenson et al.
  • 1School of GeoSciences, The University of Edinburgh, Edinburgh, UK
  • 2Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA
  • 3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
  • 4UCAR/NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA
  • 5National Center for Atmospheric Research, Boulder, Colorado, USA
  • 6NASA Goddard Institute for Space Studies and Columbia Earth Institute, New York, NY, USA
  • 7Department of Physics, Imperial College London, London, UK
  • 8CICERO, Center for International Climate and Environmental Research-Oslo, Oslo, Norway
  • 9Met Office Hadley Centre, Exeter, UK
  • 10National Institute of Water and Atmospheric Research, Lauder, New Zealand
  • 11Royal Netherlands Meteorological Institute, De Bilt, the Netherlands
  • 12Lawrence Livermore National Laboratory, Livermore, California, USA
  • 13Canadian Centre for Climate Modeling and Analysis, Environment Canada, Victoria, British Columbia, Canada
  • 14NASA Goddard Space Flight Centre, Greenbelt, Maryland, USA
  • 15Universities Space Research Association, Columbia, MD, USA
  • 16NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA
  • 17Laboratoire des Sciences du Climat et de l'Environment, Gif-sur-Yvette, France
  • 18Department of Earth and Environmental Science, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
  • 19National Institute for Environmental Studies, Tsukuba-shi, Ibaraki, Japan
  • 20GAME/CNRM, Météo-France, CNRS – Centre National de Recherches Météorologiques, Toulouse, France
  • 21Agenzia Nazionale per le Nuove Tecnologie, l'energia e lo Sviluppo Economico Sostenibile (ENEA), Bologna, Italy
  • 22Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
  • 23NASA Jet Propulsion Laboratory, Pasadena, California, USA
  • 24Lancaster Environment Centre, University of Lancaster, Lancaster, UK
  • 25Centre for Atmospheric Science, University of Cambridge, UK
  • *now at: Lancaster Environment Centre, University of Lancaster, Lancaster, UK
  • **now at: Department of Meteorology, University of Reading, UK

Abstract. Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%), nitrogen oxides (31 ± 9%), carbon monoxide (15 ± 3%) and non-methane volatile organic compounds (9 ± 2%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.

Final-revised paper