engleski

Frequency analysis of long term ozone data

Data obtained during long-term continuous ozone monitoring at different European sites were analyzed by applying Fourier transformation (FT). As expected, strong frequency signals are found for the 1 year and 1 day periods. A collective FT spectrum for different sites was calculated. This comparison confirms the existence of a common variation in ozone volume fractions with quasi periods ranging between 7 and 44 days. These frequencies are most probably connected with quasi-cyclic synoptic scale meteorological influences. As expected, strong frequency signals are found for the 1 year and 1 day periods. the relative intensity of the 1 day peak can becorrelated with the intensity of local photochemical pollution as represented by a photochemical pollution index. The relative importance of the remaining peaks are calculated for each FT spectrum and are found to describe approximately 40-44 day, 13-15 day, 8-11 day and 7 day quasi-cyclic behavior. Meteorological parameters such as temperature, pressure and relative humidity show some, but not perfect agreement with ozone concentration behavior.

ozone monitoring

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