Determining Ångström's Turbidity Coefficients: An Analysis with a Wide-Range Grating Spectrometer

The dependence of Ångstrom's turbidity parameters on the wavelength has been analyzed in the wavelength interval 0.45-0.70 μm. Measurements of aerosol optical thicknesses in this range were obtained by a wide-range grating spectrometer with a resolution of ∼ 2.5 nm. Based on such measurements, two different methods for obtaining turbidity parameters have been validated and intercompared: (a) the ratio method based on processing couples of aerosol optical depths, and (b) a linear best-fitting method based on log-log plot of aerosol optical thicknesses vs. wavelength. We found that Angstr̊m's turbidity relation is quite effective in characterizing atmospheric aerosol in low-medium turbidity cases. However, the usual method of computing the turbidity parameters on the basis of a few measurements (< 10) does not produce adequate results. Accurate estimates can be only obtained using a larger number of data points