Forcing radiative direct, 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). 

Liao, H., and J. H. Seinfeld, Effect of Clouds on Direct Aerosol Radiative Forcing of Climate, J. Geophys. Res., 103, 3781-3788... 

Liao H, Seinfeld JH (2005) Global impacts of gas-phase chemistry-aerosol interactions on direct radiative forcing by anthropogenic aerosols and ozone. J Geophys Res 110(D1) 8208. doi 10.1029/2005JD005907... 

Recent estimates of direct radiative forcing by tropospheric aerosols have employed aerosol distributions from global-scale chemical transport models and assumed aerosol properties typical of the several aerosol types. These estimates contain uncertainties both in the modeled aerosol... 

Direct radiative forcings affect directly the Earth s radiative balance for instance, added C02 absorbs infrared radiation. Indirect forcings lead to a radiative imbalance by first altering some component of the climate system that then leads to a change in radiative fluxes. An example of an indirect effect is increasing aerosol levels that produce clouds with smaller drops clouds with smaller drops are not as prone to produce precipitation, so the clouds persist longer and reflect and absorb more radiation. 

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). 

Haywood, J. M., and K. P. Shine, Multi-Spectral Calculations of the Direct Radiative Forcing of Tropospheric Sulphate and Soot Aerosols Using a Column Model, Q. J. R. Meteorol. Soc., 123, 1907-1930 (1997). 

Sokolik, I. N., and O. B. Toon, Direct Radiative Forcing by Anthropogenic Airborne Mineral Aerosols, Nature, 381, 681-683 (1996). 

Haywood, I, and Boucher, O. (2000). Estimates of the direct and indirect radiative forcing due to tropospheric aerosols a review. Rev. Geophys. 38,513-543. 

An understanding of the influence that aerosols have on climate has become increasingly important over the last several decades [3]. Primary and secondary aerosols can affect the Earth s radiative balance by scattering and absorbing light directly and can act indirectly as cloud condensation nuclei and therefore influence the distribution, duration, precipitation processes, and radiative properties of clouds. Thus, developing the ability to understand, model, and predict aerosol formation with confidence is essential to determine the impact of aerosol radiative forcing in climate models. 

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