Daniel Orozco Sanchez¹, Dairo Alegria Campo¹, Sonia Gaona Jurado¹, Alvaro Efrain Bastidas¹

¹Universidad del Cauca Popayan - Colombia

The sunphotometers are equipment that allows measuring the atmospheric attenuation of solar irradiance at certain wavelengths. >From this attenuation, and by means of a suitable selection of the wavelengths, it is possible to characterize aerosols, water vapor, ozone, oxygen, and other gases, in a vertical column through the atmosphere. The process of measurement of the photometer is based on which the atmosphere is so thin that can be considered flat, which allows to calculate the transmittance of the solar irradiance using the Beer – Bouguer – Lambert law. In this paper we present the design and construction of a sunphotometer for the measurement of the direct solar attenuation that allows determining the aerosols optical depth (AOD) and the Angstrom parameters alpha in Popayán-Colombia, giving as result the optical characterization of atmospheric aerosols in the zone. With the obtained dates, we hope to establish the aerosol climatology in the Colombian southwest. The constructed sunphotometer consists of three channels with narrow band interference filters 650nm, 535nm and 394 nm wavelengths with bandwidth of 10nm, what makes possible to collect data for different types of aerosols, e.g, those that goes from 0.1 to 1 µm, (known like aerosols in the accumulation interval), that remain long time in the atmosphere and are very interactive with the light. The photometer has been calibrated with the Langley method which is based on Beer – Bouguer – Lambert law, that is satisfied for all the considered wavelengths.