Solar cycle and seasonal behaviour of quasi two and rive day oscillations in the time variations of fOF2

SUMMARY

Seasonal and solar cycle variations of the quasi-two- and five-day oscillation amplitudes off f0F2 are evaluated by moving periodogram analysis. The 23 year time series (1964-1986) of fOF2 hourly values of Kaliningrad (54.7°N, 20.62°E), covering the solar cycles 20 and 21, is used for the analysis. Long term variations of these amplitudes are modulated by the 11-year solar cycle and are simultaneously influenced by the geomagnetic activity. The annual variation of the quasi-two- and five-day oscillation amplitudes has very clear maxima near the equinoxes. The mechanism of the influence of the travelling planetary waves in the meteor wind region by vertical plasma drift to the F2-layer electron density maximum is discussed.