Spectral aerosol optical depth and Angstrom parameters in the polluted Athens atmosphere

Summary Using ground-based spectral solar extinction data taken in the Athens atmosphere during a field survey, experimental and modeled aerosol optical depths AOD have been retrieved. The Angstrom parameters α and β were derived through spectral extinction curves determined from a log–log plot fit in four spectral intervals, e.g. UV, VIS, UV-VIS and VIS-NIR. The results reveal that exponent α derived in the shorter wavebands, is correlated with β; in the VIS-NIR range the correlation is weaker, however. It has also found that α does not depend on the Angstrom law fits, while β does. Retrieved experimental AOD obtained at longer wavelengths exhibits a daily pattern similar to turbidity β; by contrast, AOD at shorter wavelengths follows the temporal variation of α.