Direct radiative forcing by smoke from biomass burning

Science

Volumn 275, Issue 5307, 1997, Pages 1776-1778

  Hobbs, Peter V ^a   Reid, Jeffrey S ^a   Kotchenruther, Robert A ^a   Ferek, Ronald J ^a   Weiss, Ray ^b  

^a UNIVERSITY OF WASHINGTON   (United States)

^b Radiance Research   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; ATMOSPHERE; BIOMASS; BRAZIL; ENERGY BALANCE; GLOBAL CLIMATE; PRIORITY JOURNAL; RADIATION; SMOKE;

BIOMASS BURNING; RADIATION BALANCE; RADIATIVE FORCING; SMOKE;

BRAZIL;

EID: 0030620922     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.275.5307.1777     Document Type: Article

References (22)

1. -2.
2. J. T. Houghton et al., Eds., Climate Change 1995: The Science of Climate Change (Cambridge Univ. Press, Cambridge, 1995); Climate Change 1994: Radiative Forcing of Climate Change (Cambridge Univ. Press, Cambridge, 1994) [both published for the Intergovernmental Panel on Climate Change (IPCC)].
3. J. T. Houghton et al., Eds., Climate Change 1995: The Science of Climate Change (Cambridge Univ. Press, Cambridge, 1995); Climate Change 1994: Radiative Forcing of Climate Change (Cambridge Univ. Press, Cambridge, 1994) [both published for the Intergovernmental Panel on Climate Change (IPCC)].
4. -2 for the indirect forcing by all anthropogenic aerosol.
5. W. M. Hao and M.-H. Liu, Global Biogeochem. Cycles 8, 495 (1994).
6. J. E. Penner, R. E. Dickinson, C. A. O'Neill, Science 256, 1432 (1992).
7. -2. Here we are concerned with a quite different correction to Penner et al.'s estimate, namely, that resulting from the use of our measurements of the optical parameters of smoke.
8. Measurements of the optical properties of an aerosol should be made on the same sample, as was done in our study, because there is substantial interdependence and compensation among the various optical properties [O. Boucher and T. L. Anderson, J. Geophys. Res. 100, 26117 (1995)].
9. Our measurements were obtained as part of the Smoke, Clouds, and Radiation-Brazil (SCAR-B) Project in August through September 1995, during a long dry period with considerable biomass burning in Brazil.
10. The instrumentation aboard this aircraft is described by P. V. Hobbs et al. [J. Geophys. Res. 96, 18735 (1991)].
11. D. A. Hegg, D. S. Covert, M. J. Rood, P. V. Hobbs, ibid. 101, 12893 (1996).
12. C. Lin, M. Baker, R. Charlson, Appl. Opt. 12, 1356 (1973).
13. In this report "particles" or "smoke" refer to regional hazes dominated by smoke particles. At least 80 to 90% of the mass of the particles in such hazes derived directly from biomass burning. There have been no previous direct measurements of dry mass scattering efficiencies for smoke from tropical biomass burning. Approximate values can be calculated from measured particle size distributions [for example, P. Artaxo et al., J. Geophys. Res. 99, 22857 (1994)], but this method requires assumptions about the shapes and compositions of the particles.
14. J. Hansen, J. Atmos. Sci. 26, 478 (1969); W. J. Wiscombe and G. W. Grams, ibid. 33, 2440 (1976). Y. J. Kaufman and B. N. Holben [J. Geophys. Res. 101, 19433 (1996)] suggest that averaging equally over all solar zenith angles overestimates backscattering from biomass burning aerosol in the tropics by 25%, but we have not included this reduction here.
15. J. Hansen, J. Atmos. Sci. 26, 478 (1969); W. J. Wiscombe and G. W. Grams, ibid. 33, 2440 (1976). Y. J. Kaufman and B. N. Holben [J. Geophys. Res. 101, 19433 (1996)] suggest that averaging equally over all solar zenith angles overestimates backscattering from biomass burning aerosol in the tropics by 25%, but we have not included this reduction here.
16. J. Hansen, J. Atmos. Sci. 26, 478 (1969); W. J. Wiscombe and G. W. Grams, ibid. 33, 2440 (1976). Y. J. Kaufman and B. N. Holben [J. Geophys. Res. 101, 19433 (1996)] suggest that averaging equally over all solar zenith angles overestimates backscattering from biomass burning aerosol in the tropics by 25%, but we have not included this reduction here.
17. L. F. Radke et al., in Aerosols and Climate, P. V. Hobbs and M. P. McCormick, Eds. (Deepak, Hampton, VA, 1988).
18. L. F. Radke et al., in Global Biomass Burning: Atmospheric, Climatic and Biospheric Implications, J. S. Levine, Ed. (MIT Press, Cambridge, MA, 1991).
19. Y. J. Kaufman et al., J. Geophys. Res. 97, 14581 (1992).
20. P. Chylek and J. Wong, Geophys. Res. Lett. 22, 929 (1995).
21. Our measurements are for one tropical region (Brazil) during one burning season. There may be annual and geographic differences in the optical properties of smoke.
22. This work was supported by NASA grants NAGW-3750 and NAG 11709; NSF grants ATM-9400760, ATM-9412082, and ATM-9408941; U.S. Environmental Protection Agency grant CR822077; and NOAA grant NA67RJ0155 (PMEL contribution 425).