Radiative forcing in the 21st century due to ozone changes in the troposphere and the lower stratosphere

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Read Full Article (file size: 1385087 bytes) Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D9, 4292, doi:10.1029/2002JD002624, 2003 Radiative forcing in the 21st century due to ozone changes in the troposphere and the lower stratosphere M. Gauss Department of Geophysics, University of Oslo, Norway G. Myhre Department of Geophysics, University of Oslo, Norway G. Pitari Dipartimento di Fisica, Università de L'Aquila, Coppito, L'Aquila, Italy M. J. Prather Earth System Science Department, University of California at Irvine, Irvine, California, USA I. S. A. Isaksen Department of Geophysics, University of Oslo, Norway T. K. Berntsen Department of Geophysics, University of Oslo, Norway G. P. Brasseur Max-Planck-Institut für Meteorologie, Hamburg, Germany F. J. Dentener Joint Research Centre, Climate Change Unit, Ispra, Italy R. G. Derwent UK Met Office, Climate Research Division, Berks, UK D. A. Hauglustaine Institut Pierre Simon Laplace, Gif-sur-Yvette, France L. W. Horowitz Geophysical Fluid Dynamics Laboratory, NOAA, Princeton University, Princeton, New Jersey, USA D. J. Jacob Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA M. Johnson Chemistry Department, Cambridge University, Cambridge, UK K. S. Law Chemistry Department, Cambridge University, Cambridge, UK L. J. Mickley Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA J.-F. Müller IASB, Brussels, Belgium P.-H. Plantevin Chemistry Department, Cambridge University, Cambridge, UK J. A. Pyle Chemistry Department, Cambridge University, Cambridge, UK H. L. Rogers Chemistry Department, Cambridge University, Cambridge, UK D. S. Stevenson Institute for Meteorology, University of Edinburgh, Edinburgh, UK J. K. Sundet Department of Geophysics, University of Oslo, Norway M. van Weele Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands O. Wild Frontier Research System for Global Change, Yokohama, Japan Abstract Radiative forcing due to changes in ozone is expected for the 21st century. An assessment on changes in the tropospheric oxidative state through a model intercomparison (“OxComp”) was conducted for the IPCC Third Assessment Report (IPCC-TAR). OxComp estimated tropospheric changes in ozone and other oxidants during the 21st century based on the “SRES” A2p emission scenario. In this study we analyze the results of 11 chemical transport models (CTMs) that participated in OxComp and use them as input for detailed radiative forcing calculations. We also address future ozone recovery in the lower stratosphere and its impact on radiative forcing by applying two models that calculate both tropospheric and stratospheric changes. The results of OxComp suggest an increase in global-mean tropospheric ozone between 11.4 and 20.5 DU for the 21st century, representing the model uncertainty range for the A2p scenario. As the A2p scenario constitutes the worst case proposed in IPCC-TAR we consider these results as an upper estimate. The radiative transfer model yields a positive radiative forcing ranging from 0.40 to 0.78 W m⁻² on a global and annual average. The lower stratosphere contributes an additional 7.5–9.3 DU to the calculated increase in the ozone column, increasing radiative forcing by 0.15–0.17 W m⁻². The modeled radiative forcing depends on the height distribution and geographical pattern of predicted ozone changes and shows a distinct seasonal variation. Despite the large variations between the 11 participating models, the calculated range for normalized radiative forcing is within 25%, indicating the ability to scale radiative forcing to global-mean ozone column change. Published 13 May 2003. Index Terms: 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0341 Atmospheric Composition and Structure: Middle atmosphere—constituent transport and chemistry (3334). Read Full Article (file size: 1385087 bytes) Cited by Citation: Gauss, M., et al. (2003), Radiative forcing in the 21st century due to ozone changes in the troposphere and the lower stratosphere, J. Geophys. Res., 108(D9), 4292, doi:10.1029/2002JD002624. Copyright 2003 by the American Geophysical Union.

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