Three-wavelength sun-photometer for aerosol characterization

A three-wavelength sun-photometer was designed and built. The attenuation of direct solar light, at wavelengths of 0.38 mu m, 0.50 mu m and 1.00 mu m were measured. Silicon photodiodes and interference filters of 10 nm FWHM were used. Aerosols were characterized by Angstrom turbidity formula in terms of coefficients alpha and beta and by Moon's model in terms of the precipitable water content, w, and the amount of dust particles per unit volume, d. Aerosol attenuation was calculated from the slope of Langley's plots. Several measurements were performed in the city of San Luis (33.27 S, 66.35 W) during summer and autumn seasons of 1996. Results corresponded to a very clean atmosphere (beta < 0.05, d < 300 particles per cubic centimeter). Weather was extremely dry during most of measurements.