Observations of wave activity in the ionosphere over South Africa in geomagnetically quiet and disturbed periods

Waves of periods 30-50 min were observed in the F2 layer during the daytime on five out of the eighteen days analysed, on four geomagnetically active days and on one quiet day. On the geomagnetically active day of 27 July 2010, waves of periods 1-2.5 min occurred in the evening and night hours. These waves appeared simultaneously with 1-2.5 min fluctuations of horizontal components of the local geomagnetic field. We suppose that the 1-2.5 min ionospheric oscillations are a response to the geomagnetic micropulsations.