Scattering, Absorption, and Extinction Coefficients from Mie Theory

Denver during winter, elemental carbon was responsible for about 40% of visibility reduction. The disproportionately large influence of black carbon on light extinction, relative to its concentration, arises in part, as we will see, because black carbon is more effective than nonabsorbing aerosol particles (such as sulfates and nitrates) of the same size in attenuating light (Faxvog and Roessler 1978). 

3 SCATTERING, ABSORPTION, AND EXTINCTION COEFFICIENTS FROM MIE THEORY 

Aerosol scattering, absorption, and extinction coefficients are functions of the particle size, the complex refractive index of the particles m, and the wavelength X of the incident light. The extinction coefficient for a monodisperse ensemble of particles was given in terms of the dimensionless extinction efficiency by (15.27). With a population of differentsized particles of identical refractive index m with a number size distribution function of n(Dp), the extinction coefficient is given by1 

It is frequently useful to express bexl in terms of the aerosol mass distribution function 

Similarly, the mass scattering and mass absorption efficiencies are 

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