Statistical evaluation of selected air pollutants in Athens, Greece

Abstract

AbstractA statistical evaluation of the air pollution situation in Athens for the year 1982 is presented. This analysis refers to NO2, NO, O3 and SO2 concentration levels measured at the National Observatory of Athens (NOA) with a fully automatic monitoring station. The seasonal, weekly and daily variations of the above pollutants are in agreement with the corresponding activities in the city which are responsible for these emissions. Auto‐ and cross‐correlation techniques are applied to the pollutants for January and July. It is found that all pollutants exhibit a well defined oscillatory behaviour because of their diurnal peaks in both months, except for NO2 in January whose auto‐correlation function shows no regular shape. For the same reason the January NO‐NO2 cross‐correlation function behaves in the same way; the pairs NO‐O3 and NO2‐O3 exhibit a clear oscillatory pattern. The spectral estimate method is also employed to the above pollutants for the two months in question. The energy content of O3, for instance, in July shows to be concentrated around a frequency corresponding to a periodicity of 24 hours.