Atmos. Chem. Phys., 13, 2423-2434, 2013
www.atmos-chem-phys.net/13/2423/2013/
doi:10.5194/acp-13-2423-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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
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.

Citation: Samset, B. H., Myhre, G., Schulz, M., Balkanski, Y., Bauer, S., Berntsen, T. K., Bian, H., Bellouin, N., Diehl, T., Easter, R. C., Ghan, S. J., Iversen, T., Kinne, S., Kirkevåg, A., Lamarque, J.-F., Lin, G., Liu, X., Penner, J. E., Seland, Ø., Skeie, R. B., Stier, P., Takemura, T., Tsigaridis, K., and Zhang, K.: Black carbon vertical profiles strongly affect its radiative forcing uncertainty, Atmos. Chem. Phys., 13, 2423-2434, doi:10.5194/acp-13-2423-2013, 2013.
 
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