Determination of Ångström and Schüepp's Parameters from Ground-based Spectral Measurements of Beam Irradiance in the Ultraviolet and Visible Spectrum in Athens, Greece

摘要

— This work estimates the Ångström coefficients, assuming a linear behavior of the natural logarithm of aerosol optical thickness, ln δα(λ), versus the natural logarithm of wavelength, ln λ, in the urban environment of Athens for a period of one year. The calculation of the coefficients α, β, was carried out using records of spectral beam irradiance in the 320–575 nm spectral range. The seasonal and diurnal variation of the coefficients shows different features with generally higher values of β and lower values of α in summertime. The Ångström coefficients are investigated with respect to various wind regimes and the results are discussed with a view to air pollution sources, climatic and topographic characteristics of the Athens basin. A similar study is also carried out for the Schüepp's turbidity parameter.