Articles | Volume 13, issue 5
Atmos. Chem. Phys., 13, 2347–2379, 2013
Atmos. Chem. Phys., 13, 2347–2379, 2013

Research article 01 Mar 2013

Research article | 01 Mar 2013

Intercomparison of shortwave radiative transfer schemes in global aerosol modeling: results from the AeroCom Radiative Transfer Experiment

C. A. Randles1,2, S. Kinne3, G. Myhre4, M. Schulz5, P. Stier6, J. Fischer7, L. Doppler7,8, E. Highwood9, C. Ryder9, B. Harris9, J. Huttunen10, Y. Ma11, R. T. Pinker11, B. Mayer12, D. Neubauer13,14, R. Hitzenberger13,14, L. Oreopoulos15, D. Lee15,16, G. Pitari17, G. Di Genova17,18, J. Quaas19, F. G. Rose20,21, S. Kato21, S. T. Rumbold22, I. Vardavas23, N. Hatzianastassiou24, C. Matsoukas25, H. Yu15,26, F. Zhang26, H. Zhang27, and P. Lu27 C. A. Randles et al.
  • 1GESTAR/Morgan State University, Baltimore, Maryland, USA
  • 2NASA Goddard Space Flight Center (GSFC) Atmospheric Chemistry and Dynamics Lab, Greenbelt, MD, USA
  • 3Max Plank Institute for Meteorology, Hamburg, Germany
  • 4Center for International Climate and Environmental Research-Oslo (CICERO), Oslo, Norway
  • 5Meteorologisk Institutt, Oslo, Norway
  • 6Department of Physics, University of Oxford, Oxford, UK
  • 7Institut für Weltraumwissenschaften, Freie Universität, Berlin, Germany
  • 8LATMOS-IPSL, Paris, France
  • 9Department of Meteorology, University of Reading, Reading, UK
  • 10Finnish Meteorological Institute, Kuopio, Finland
  • 11University of Maryland, Department of Atmospheric and Oceanic Science, Maryland, USA
  • 12Ludwig-Maximilians-Universitaet, Munich, Germany
  • 13Research Platform: ExoLife, University of Vienna, Vienna, Austria
  • 14Faculty of Physics, University of Vienna, Vienna, Austria
  • 15NASA GSFC Climate and Radiation Laboratory, Greenbelt, Maryland, USA
  • 16Seoul National University, Seoul, Republic of Korea
  • 17Department of Physical and Chemical Sciences, University of L'Aquila, L'Aquila, Italy
  • 18Space Academy Foundation, Fucino Space Center, Ortucchio, Italy
  • 19Institut für Meteorologie, Universität Leipzig, Leipzig, Germany
  • 20SSAI, Hampton, VA, USA
  • 21NASA Langley Research Center (LaRC), Hampton, Virginia, USA
  • 22UK Met Office (UKMO) Hadley Center, Exeter, UK
  • 23Department of Physics, University of Crete, Crete, Greece
  • 24Laboratory of Meteorology, Department of Physics, University of Ioannina, Ioannina, Greece
  • 25Department of Environment, University of the Aegean, Aegean, Greece
  • 26Earth System Science Interdisciplinary Center (ESSIC), University of Maryland, College Park, Maryland, USA
  • 27Laboratory for Climate Studies, CMA, National Climate Center, Beijing, China

Abstract. In this study we examine the performance of 31 global model radiative transfer schemes in cloud-free conditions with prescribed gaseous absorbers and no aerosols (Rayleigh atmosphere), with prescribed scattering-only aerosols, and with more absorbing aerosols. Results are compared to benchmark results from high-resolution, multi-angular line-by-line radiation models. For purely scattering aerosols, model bias relative to the line-by-line models in the top-of-the atmosphere aerosol radiative forcing ranges from roughly −10 to 20%, with over- and underestimates of radiative cooling at lower and higher solar zenith angle, respectively. Inter-model diversity (relative standard deviation) increases from ~10 to 15% as solar zenith angle decreases. Inter-model diversity in atmospheric and surface forcing decreases with increased aerosol absorption, indicating that the treatment of multiple-scattering is more variable than aerosol absorption in the models considered. Aerosol radiative forcing results from multi-stream models are generally in better agreement with the line-by-line results than the simpler two-stream schemes. Considering radiative fluxes, model performance is generally the same or slightly better than results from previous radiation scheme intercomparisons. However, the inter-model diversity in aerosol radiative forcing remains large, primarily as a result of the treatment of multiple-scattering. Results indicate that global models that estimate aerosol radiative forcing with two-stream radiation schemes may be subject to persistent biases introduced by these schemes, particularly for regional aerosol forcing.

Final-revised paper