Application of the Chandrasekhar mean to aerosol optical parameters

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Abstract
In an attempt to characterize the optical properties of aerosols using a small number of parameters, a Chandrasekhar mean of the volume attenuation coefficients and the asymmetry factor are employed. The total reflection, absorption and transmission obtained using a one‐dimensional radiation model of the atmosphere are compared, for the case of spectrally variable attenuation coefficients and asymmetry factor, and for the case of spectrally averaged parameters. The wavelength‐independent parameters appear to describe reasonably well the absorption and scattering due to aerosols in a turbid atmosphere. This may serve efficiently for computing radiative heating profiles. Besides providing a simplified description of the aerosol's optical properties, two applications are considered. It is found that the wavelength corresponding to the average volume attenuation coefficient is about 0.7 μm, and that the measurement of parameters at this wavelength should provide a representative value for the complete solar spectrum. Secondly, these parameters offer the possibility of considerably reducing calculations whenever aerosols are to be included in elaborate climate models. As an illustration, a parameterization for wet aerosols is given.