Articles | Volume 6, issue 7
Atmos. Chem. Phys., 6, 1815–1834, 2006
Atmos. Chem. Phys., 6, 1815–1834, 2006

  29 May 2006

29 May 2006

An AeroCom initial assessment – optical properties in aerosol component modules of global models

S. Kinne1, M. Schulz2, C. Textor2, S. Guibert2, Y. Balkanski2, S. E. Bauer3, T. Berntsen4, T. F. Berglen4, O. Boucher5,6, M. Chin7, W. Collins8, F. Dentener9, T. Diehl10, R. Easter11, J. Feichter1, D. Fillmore8, S. Ghan11, P. Ginoux12, S. Gong13, A. Grini4, J. Hendricks14, M. Herzog12, L. Horowitz12, I. Isaksen4, T. Iversen4, A. Kirkevåg4, S. Kloster1, D. Koch3, J. E. Kristjansson4, M. Krol16, A. Lauer14, J. F. Lamarque8, G. Lesins17, X. Liu15, U. Lohmann18, V. Montanaro19, G. Myhre4, J. Penner15, G. Pitari19, S. Reddy12, O. Seland4, P. Stier1, T. Takemura20, and X. Tie8 S. Kinne et al.
  • 1Max-Planck-Institut für Meteorologie, Hamburg, Germany
  • 2Laboratoire des Sciences du Climat et de l’environnement, Gif-sur-Yvette, France
  • 3The Earth Institute at Columbia University, New York, NY, USA
  • 4University of Oslo, Department of Geosciences, Oslo, Norway
  • 5Laboratoire d’Optique Atmosph’erique, USTL/CNRS, Villeneuve d’Ascq, France
  • 6Hadley Centre, Met Office, Exeter, UK
  • 7NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 8NCAR, Boulder, Colorado, USA
  • 9EC, Joint Research Centre, IES, Climate Change Unit, Ispra, Italy
  • 10Goddard Earth Sciences and Technology Center, UMBC, Baltimore, MD, USA
  • 11Batelle, Pacific Northwest National Laboratory, Richland, USA
  • 12NOAA, Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
  • 13ARQM Meteorological Service Canada, Toronto, Canada
  • 14DLR, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
  • 15University of Michigan, Ann Arbor, MI, USA
  • 16Institute for Marine and Atmospheric Research Utrecht (IMAU) Utrecht, The Netherlands
  • 17Dalhousie University, Halifax, Canada
  • 18ETH Zürich, Switzerland
  • 19Universita degli Studi L’Aquila, L’Aquila, Italy
  • 20Kyushu University, Fukuoka, Japan

Abstract. The AeroCom exercise diagnoses multi-component aerosol modules in global modeling. In an initial assessment simulated global distributions for mass and mid-visible aerosol optical thickness (aot) were compared among 20 different modules. Model diversity was also explored in the context of previous comparisons. For the component combined aot general agreement has improved for the annual global mean. At 0.11 to 0.14, simulated aot values are at the lower end of global averages suggested by remote sensing from ground (AERONET ca. 0.135) and space (satellite composite ca. 0.15). More detailed comparisons, however, reveal that larger differences in regional distribution and significant differences in compositional mixture remain. Of particular concern are large model diversities for contributions by dust and carbonaceous aerosol, because they lead to significant uncertainty in aerosol absorption (aab). Since aot and aab, both, influence the aerosol impact on the radiative energy-balance, the aerosol (direct) forcing uncertainty in modeling is larger than differences in aot might suggest. New diagnostic approaches are proposed to trace model differences in terms of aerosol processing and transport: These include the prescription of common input (e.g. amount, size and injection of aerosol component emissions) and the use of observational capabilities from ground (e.g. measurements networks) or space (e.g. correlations between aerosol and clouds).

Final-revised paper