Tropospheric aerosol climate forcing in clear-sky satellite observations over the oceans

Science

Volumn 283, Issue 5406, 1999, Pages 1299-1303

  Haywood, J M ^a   Ramaswamy, V ^b   Soden, B J ^b  

^a MET OFFICE   (United Kingdom)

^b PRINCETON UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CLIMATE FORCING; TROPOSPHERE;

AEROSOL; ARTICLE; ATMOSPHERIC DISPERSION; GLOBAL CLIMATE; METEOROLOGY; PRIORITY JOURNAL; SOLAR RADIATION; TROPOSPHERE;

EID: 0033605243     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.283.5406.1299     Document Type: Article

References (46)

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17. The radiation scheme used combines the delta-Eddington method with an exponential-sum fitting technique to handle multiple-scattering and molecular absorption (12). The parameterization has been developed and calibrated with high spectral resolution line-by-line adding-doubling solutions of Ramaswamy and Freidenreich [J. Geophys. Res. 103, 23255 (1998)]. [See also S. M. Freidenreich and V. Ramaswamy, Ninth Conference on Atmospheric Radiation, Long Beach, CA, American Meteorological Society, February 1997, pp. 129-130; S. M. Freidenreich and V. Ramaswamy, in preparation.]
18. The radiation scheme used combines the delta-Eddington method with an exponential-sum fitting technique to handle multiple-scattering and molecular absorption (12). The parameterization has been developed and calibrated with high spectral resolution line-by-line adding-doubling solutions of Ramaswamy and Freidenreich [J. Geophys. Res. 103, 23255 (1998)]. [See also S. M. Freidenreich and V. Ramaswamy, Ninth Conference on Atmospheric Radiation, Long Beach, CA, American Meteorological Society, February 1997, pp. 129-130; S. M. Freidenreich and V. Ramaswamy, in preparation.]
19. The radiation scheme used combines the delta-Eddington method with an exponential-sum fitting technique to handle multiple-scattering and molecular absorption (12). The parameterization has been developed and calibrated with high spectral resolution line-by-line adding-doubling solutions of Ramaswamy and Freidenreich [J. Geophys. Res. 103, 23255 (1998)]. [See also S. M. Freidenreich and V. Ramaswamy, Ninth Conference on Atmospheric Radiation, Long Beach, CA, American Meteorological Society, February 1997, pp. 129-130; S. M. Freidenreich and V. Ramaswamy, in preparation.]
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36. As an indication of the sensitivity to uncertainties in water vapor, additional calculations for July 1988, with European Center for Medium Range Weather Forecasts (ECMWF) assimilated analyses of water vapor in place of the GCM water vapor fields, revealed differences of less than 20% from the biases shown in Fig. 1A.
37. Offline calculations performed with daily-mean rather than monthly-mean wind speeds yielded sea-salt concentrations that differ by ∼ 15% on average. This difference is much smaller than the uncertainty in the mass-loading versus wind speed relation (19).
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39. 2 to sulfate. The connection between sea-salt and sulfur cycles is also discussed by H. Sievering et al. [ibid. 360, 571 (1992)] and N. A. Clegg and R. Toumi [J. Geophys. Res. 103, 31095 (1998)]. Thus, for particles in the radiatively important size regime, the radiative contributions of sea-salt and sulfur may be linked. P. Quinn et al. [ibid., p. 16547] point out that sea-salt controls the aerosol optical properties in the southern ocean in both the sub-and supermicrometer modes.
40. 2 to sulfate. The connection between sea-salt and sulfur cycles is also discussed by H. Sievering et al. [ibid. 360, 571 (1992)] and N. A. Clegg and R. Toumi [J. Geophys. Res. 103, 31095 (1998)]. Thus, for particles in the radiatively important size regime, the radiative contributions of sea-salt and sulfur may be linked. P. Quinn et al. [ibid., p. 16547] point out that sea-salt controls the aerosol optical properties in the southern ocean in both the sub-and supermicrometer modes.
41. 2 to sulfate. The connection between sea-salt and sulfur cycles is also discussed by H. Sievering et al. [ibid. 360, 571 (1992)] and N. A. Clegg and R. Toumi [J. Geophys. Res. 103, 31095 (1998)]. Thus, for particles in the radiatively important size regime, the radiative contributions of sea-salt and sulfur may be linked. P. Quinn et al. [ibid., p. 16547] point out that sea-salt controls the aerosol optical properties in the southern ocean in both the sub-and supermicrometer modes.
42. 2 to sulfate. The connection between sea-salt and sulfur cycles is also discussed by H. Sievering et al. [ibid. 360, 571 (1992)] and N. A. Clegg and R. Toumi [J. Geophys. Res. 103, 31095 (1998)]. Thus, for particles in the radiatively important size regime, the radiative contributions of sea-salt and sulfur may be linked. P. Quinn et al. [ibid., p. 16547] point out that sea-salt controls the aerosol optical properties in the southern ocean in both the sub-and supermicrometer modes.
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45. E. C. Monahan, J. Phys. Oceanogr. 1, 139 (1971)]. Calculations performed with the assumption that the whitecaps are diffuse reflectors with an albedo of 0.6 suggest that the global surface reflectance is likely to decrease rather than increase as a function of wind speed; this cannot, therefore, explain the bias between model and observed reflected irradiances at the TOA seen in Fig. 1A.
46. We thank P. Kasibhatla and J. Langner for providing the sulfate climatologies, W. Cooke for providing the black carbon climatologies, I. Tegen for providing the dust climatologies, the NASA/Langley Distributed Active Archive Center (DAAC) for providing the ERBE data, the NASA/Jet Propulsion Laboratory DAAC for providing the SSMI data, and A. Broccoli, D. Schwarzkopf, R. Stouffer, and two anonymous reviewers for their comments and suggestions.