ANNUAL, SEMIANNUAL AND SEASONAL-VARIATIONS OF THE TOTAL OZONE CONTENTDERIVED FROM MEASUREMENTS MADE BY THE TOMS INSTRUMENT FOR THE REGION OF ST-PETERSBURG

Data obtained from daily observations made by the Total Ozone Mapping Spectrometer TOMS of the ''Nimbus-7'' satellite and processed in order to derive maps of the total ozone content in the atmosphere over a ti me period from January, 1979 to January, 1992 were used for the analys is of variations of the total ozone content within the region of St. P etersburg. Fourier analysis of the mean monthly values of the total oz one content was made to calculate amplitudes, phases and relative cont ributions of the first three harmonics to the total variability of the total ozone content. Results obtained from the studies were discussed in the context of recently made conclusion about the maximum annual d istribution of the total ozone content in the atmosphere of middle lat itudes and the fact, that decrease of the total ozone determined by an thropogenic factors exceeded 0.8% per year.