Estimation of total atmospheric pollution using global radiation data: introduction of a novel clear day selection methodology

This work investigates the possibility of determining the degree of atmospheric pollution over the small Greek city of Serres based solely on measurements of global solar radiation and some simple meteorological variables. Hourly data of solar irradiance on an horizontal plane are recorded simultaneously together with relative humidity and wind speed. Along with some traditional techniques for selecting the clear sky days of the period examined, the statistical coefficients of skewness and kurtosis of the daily distributions of hourly radiation data have been employed with reasonable success. Indeed, for the cloudless days of this study, the values of the above quantities are confined within narrow ranges which provide a criterion for their identification from the cloudy days. Comparison of global radiation data under clear sky conditions with reference values from a suitable theoretical model of literature, in combination with the results of a recent study for the nearby city of Thessaloniki, provides evidence that there is virtually no atmospheric pollution in Serres. Correlation of the observed deviations between measurements and predictions with recorded meteorological data lends further support to the above argument.