The fluctuations of 27-day periodicities of the Total Ozone Content at middle latitudes

The time variations of daily values of the Total Ozone Content (TOC) during 1978-1992 at stations Irkutsk, Collm, Madrid and Saskatoon were investigated. These stations are located in the middle latitudes but have essentially different longitudes. The TOMS-database (satellite Nimbus-7) was used. The multi-correlation periodogramanalysis with sliding step I month was applied. The fluctuations with the periods laying in rather wide band including 27 day variations (2139 days) were revealed. Amplitudes of these fluctuations have a well defined annual course with a maximum in the winter and a minimum in the summer. The variations of amplitudes of 27-day fluctuations contain an annual wave and quasibiennial oscillations with periods 20-28 months. At Saskatoon and Irkutsk during years close to maxima of solar activity (1980 and 1990) the amplitudes of 27-day TOC fluctuations are the greatest. The significant correlation between amplitudes of fluctuations at considered middle-latitude stations practically without of phase lag is found out. Correlation functions are quasiperiodical with maxima of correlation coefficients each two years. It is possible to explain the results by joint influence of 27-day variations of solar activity connected with rotation of the Sun and planetary atmospheric waves activity. The regular 27-day TOC fluctuations can be considered as climatic parameters of TOC variability in the Earth's atmosphere.