Fourier Analysis of the mean monthly Nox Concentration in the Athens basin

In the present work, Fourier Analysis is applied to the mean monthly NOx concentrations of the period
1989-1999, for a network of 7 stations. Treating NO and NO2 as a single primary pollutant, we succeeded
the assessment of NOx concentrations. The main causes of NOx emissions in urban areas are
the road traffic and the industrial activity.
The annual variation of NOx concentration is well described with only two harmonic components,
which explain over 90% of the total variance. The spatial distribution of the time of maximum, for every
one of the two harmonic components in Athens basin, is also presented.