Angstrom turbidity and ozone column estimations from spectral solar irradiance in a semi-desertic environment in Spain

Angstrom parameters are commonly used for modelling the solar radiation extinction by aerosols. Detailed knowledge of these parameters in as many places as possible is desirable since many applications need this kind of information: satellite products assessment, clear sky models benchmarking, spectral modelling, etc. Experimental determinations of the Angstrom turbidity and wavelength exponent have been made for a semi-desertic area in the south-east of Spain using a double monochromator spectroradiometer. Experimental measurements of direct-beam spectral irradiance have been made about every 20 min during one year (from october 2005 to september 2006). Angstrom turbidity has a noticeable variability during the year, showing a seasonal characteristic behaviour. Low turbidity values were found during autumn and winter and quite large values can be observed in spring and summer days. The eventual values of high turbidity with low wavelength exponent found could indicate Saharan dust outbreaks events. In addition, total ozone column have been experimentally estimated from spectral measurements in the Huggins absorption band. The results showed a general agreement with the values extracted from the TOMS web site.