Determining Ångström’s turbidity coefficients: An analysis with a wide-range grating spectrometer

Abstract

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 measurementstwo different methods for obtaining turbidity parameters have been validated and intercompared: (a) the ratio method based on processing couples of aerosol optical depthsand (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. Howeverthe 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. © 1993 Elsevicr Science Publishing Co., Inc.