Stratospheric volcanic aerosols: A model study of interactive influences upon solar radiation

Considerable differences exist within the literature concerning the effect of volcanically induced stratospheric aerosols upon the earth's planetary albedo. In order to investigate these discrepancies, we have developed a two-stream approximation which is shown to be in good agreement with more detailed calculations. The model employs aerosol radiative properties which are determined from a separate Mie scattering calculation. We then make systematic changes within the model to illustrate the individual effects of Rayleigh scattering, the angular dependence of both Rayleigh and aerosol scattering, and full-flux versus single-wavelength calculations. When all interactive effects are included, the aerosol influence upon planetary albedo is reduced, relative to the usual single wavelength calculations, by more than a factor of two. This finding resolves the aforementioned discrepancies.