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. 2003 May 27;100(11):6319-24.
doi: 10.1073/pnas.0731897100. Epub 2003 May 13.

Global atmospheric black carbon inferred from AERONET

Makiko Sato  1 , James Hansen, Dorothy Koch, Andrew Lacis, Reto Ruedy, Oleg Dubovik, Brent Holben, Mian Chin, Tica Novakov
Affiliations

Global atmospheric black carbon inferred from AERONET

Makiko Sato et al. Proc Natl Acad Sci U S A. .

Abstract

AERONET, a network of well calibrated sunphotometers, provides data on aerosol optical depth and absorption optical depth at >250 sites around the world. The spectral range of AERONET allows discrimination between constituents that absorb most strongly in the UV region, such as soil dust and organic carbon, and the more ubiquitously absorbing black carbon (BC). AERONET locations, primarily continental, are not representative of the global mean, but they can be used to calibrate global aerosol climatologies produced by tracer transport models. We find that the amount of BC in current climatologies must be increased by a factor of 2-4 to yield best agreement with AERONET, in the approximation in which BC is externally mixed with other aerosols. The inferred climate forcing by BC, regardless of whether it is internally or externally mixed, is approximately 1 W/m2, most of which is probably anthropogenic. This positive forcing (warming) by BC must substantially counterbalance cooling by anthropogenic reflective aerosols. Thus, especially if reflective aerosols such as sulfates are reduced, it is important to reduce BC to minimize global warming.

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Figures

Fig. 1.
Fig. 1.
Aerosol absorption (1,000 × τa) at λ = 550 nm based on the chemical transport models of Koch (Left) and Chin (Right).
Fig. 2.
Fig. 2.
Comparison of τa from Koch and Chin models with AERONET observations at 440 and 670 nm.
Fig. 3.
Fig. 3.
Comparison of ω from Koch and Chin models, using aerosol optical properties described in our text, with AERONET observations for the “full” soil dust absorption coefficient of Patterson et al. (17).
Fig. 4.
Fig. 4.
Difference between modeled and AERONET-measured τa, averaged over grid boxes with AERONET stations, as a function of the factors by which the models' BC and OC amounts are multiplied. The fifth column is the rms for the four AERONET wavelengths.
Fig. 5.
Fig. 5.
Single scattering albedo ω (reff, λ) for BC, OC, and soil dust aerosols.
Fig. 6.
Fig. 6.
Climate forcing by BC based on the Koch and Chin models modified by AERONET.
See this image and copyright information in PMC

References

    1. Intergovernmental Panel on Climate Change (1996) Climate Change 1995: The Science of Climate Change, eds. Houghton, J. T., Meira, L. G., Callander, B. A., Harris, N., Kattenberg, A. & Maskell, K. (Cambridge Univ. Press, Cambridge, U.K.).
    1. Intergovernmental Panel on Climate Change (2001) Climate Change 2001: The Scientific Basis, eds. Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K. & Johnson, C. A. (Cambridge Univ. Press, Cambridge, U.K.).
    1. Jacobson, M. Z. (2001) Nature 409, 695–697. - PubMed
    1. Hansen, J. E. & Sato, M. (2001) Proc. Natl. Acad. Sci. USA 98, 14778–14783. - PMC - PubMed
    1. Bergstrom, R. W., Russell, P. B. & Hignett, P. (2002) J. Atmos. Sci. 59, 567–577.

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