Atmospheric turbidity parameters in the highly polluted site of Athens basin

Data on atmospheric turbidity coefficients, i.e. Linke factor T L and Angstrom coefficient β, calculated from measurements of broad-band filter at Athens Observatory (NOA), are reported. A linear model fitted to β vs T L for Athens is similar to the models reported for Avignon (France) and Dhahran (Saudi Arabia). The variation in the monthly average values of β and T L is of similar trend to that of Avignon and Dhahran. However, Athens has shown higher values of atmospheric turbidity coefficients than Avignon and similar turbidity levels to Dhahran. Finally, the long-term variation of the monthly mean values of the mid-day turbidity parameters and the broad-band direct and diffuse irradiances under cloudless skies are evaluated for the same period. The turbidity trends in conjunction with the trends of solar radiation components reflect the rapid urbanization and industrialization of the Athens basin.