Forcing radiative sulfate aerosols

Ghan, S. J., and R. C. Easter, Comments on A Limited-Area-Model Case Study of the Effects of Sub-Grid Scale Variations in Relative Humidity and Cloud upon the Direct Radiative Forcing of Sulfate Aerosol, Geophys. Res. Lett., 25, 1039-1040 (1998). 

A number of studies have employed the box model (22.68) to estimate direct aerosol forcing by sulfate aerosols (Charlson et al., 1991, 1992 Pilinis et al., 1995 Nemesure et al., 1995 Penner et al., 1994). These studies consider (22.68) to represent the radiative forcing in a column of air extending from the surface to the top of the atmosphere. The mean optical depth is computed as the product of the aerosol mass scattering coefficient... 

FIGURE 14-29 Calculated direct radiative forcing due to sulfate aerosol particles (adapted from Penner et al., 1998). 

Van Dorland, R.. F.J. Dentener, and J. Lelieveld, Radiative forcing due to tropospheric ozone and sulfate aerosols. J.Geophys.Res.. 102.28079-28100, 1997. 

Kiehl JT, Schneider TL, Rasch PJ, Barth MC, Wong J (2000) Radiative forcing due to sulfate aerosols from simulations with the National Center for Atmospheric Research Community Climate Model, Version 3. JGeophysRes 105 1441-1457... 

FIGURE 7 (a) Radiative forcing from greenhoitse gases, sulfate aerosols (direct and indirect effect),... 

Today, the anthropogenic emissions of SO, primarily from fossil fuel combustion, largely dominate the sulfur flux into in the atmosphere on the global scale. Climate models have determined the corresponding direct and indirect impacts on radiative forcing, but large uncertainties remain in these estimates. In fact, predictions of future climate need to account not only for the effects of sulfate aerosols, but also for the contributions of mineral dust, black carbon, organic carbon, and sea salt. The current view is that atmospheric particles should be treated as multicomponent, mul-... 

FIGURE 7 The radiative forcing for contemporary production of sulfate aerosols simulated by ECHAM (Roeckneretrt/., 1999). 

Aerosol Radiative Forcing Efficiency The radiative forcing of an aerosol species can be normalized by its column mass burden to produce a radiative forcing efficiency per unit mass AG. For sulfate aerosol, for example, one obtains... 

Global-mean direct radiative forcing from anthropogenic sulfate aerosols is thus given by... 

Karl, T. R., Knight, R. W., Kukla, G., and Gavin, J. (1995) Evidence for radiative effects of anthropogenic sulfate aerosols in the observed climate record, in Aerosol Forcing of Climate, edited by R. J. Charlson and J. Heintzenberg. Wiley, New York, pp. 361-382. 

Sulfur 10-200% increase6 in surface area of sulfate particles Increased aerosol mass loading, change in radiative forcing... 

Haywood, J. M., and V. Ramaswamy, Global Sensitivity Studies of the Direct Radiative Forcing Due to Anthropogenic Sulfate and Black Carbon Aerosols, J. Geophys. Res., 103, 6043-6058 (1998b). 

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