Articles | Volume 13, issue 5
Atmos. Chem. Phys., 13, 2423–2434, 2013
Atmos. Chem. Phys., 13, 2423–2434, 2013
Research article
01 Mar 2013
Research article | 01 Mar 2013

Black carbon vertical profiles strongly affect its radiative forcing uncertainty

B. H. Samset1, G. Myhre1, M. Schulz2, Y. Balkanski3, S. Bauer4, T. K. Berntsen1, H. Bian5, N. Bellouin6, T. Diehl7,8, R. C. Easter9, S. J. Ghan9, T. Iversen2,11,16, S. Kinne10, A. Kirkevåg2, J.-F. Lamarque12, G. Lin13, X. Liu9, J. E. Penner13, Ø. Seland2, R. B. Skeie1, P. Stier14, T. Takemura15, K. Tsigaridis4, and K. Zhang9,10 B. H. Samset et al.
  • 1Center for International Climate and Environmental Research – Oslo (CICERO), Oslo, Norway
  • 2Norwegian Meteorological Institute, Oslo, Norway
  • 3Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France
  • 4NASA Goddard Institute for Space Studies and Columbia Earth Institute, New York, NY, USA
  • 5Joint Center for Earth Systems Technology, University of Maryland Baltimore County, MD, USA
  • 6Met Office Hadley Centre, Exeter, UK
  • 7NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 8Universities Space Research Association, Columbia, MD, USA
  • 9Pacific Northwest National Laboratory, Richland, WA, USA
  • 10Max Planck Institute for Meteorology, Hamburg, Germany
  • 11Department of Geosciences, University of Oslo, Oslo, USA
  • 12NCAR Earth System Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
  • 13Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA
  • 14Department of Physics, University of Oxford, Oxford, UK
  • 15Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan
  • 16ECMWF, Shinfield Park, RG2 9AX, Reading, UK

Abstract. The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20% of the present uncertainty in modeled BC direct radiative forcing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Additionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40% of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing characteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere.

Final-revised paper