Why measure Aerosol Single-Scattering Albedo?
• One of the key aerosol parameters necessary to derive local estimates of direct aerosol radiative forcing. Define Forcing • Define forcing: an externally imposed perturbation to the radiative balance of the earth. Implies need to separate anthropogenic and natural contributions. • This equation represents an annual mean forcing at TOA, instantaneous forcings can be much larger. Surface forcings can also be much larger. • This equation (or close variant) being used in current models of aerosol forcing, e.g., IPCC estimates. • Corresponding equation for GHG much simpler, as radiative properties of all CO2 molecules are identical. Not so for aerosols. • B depends on zenith angle, can t measure directly. So we measure a surrogate instead. Both are integral properties of angular scattering function.
