THE ASSOCIATION OF PHASE CHANGES OF IONOSPHERE-PROPAGATING RADIO WAVES AND GEOMAGNETIC VARIATIONS

Abstract

Classification of Doppler frequency changes of ionosphere-propagating radio waves has been made with special emphasis on their possible relationships with simultaneous geomagnetic variations. The Doppler frequency changes are suitably divided into two classes: rapid variations and slow changes, according to whether or not the time scale of a change is shorter than about 4 minutes. The overall coincidence between geomagnetic variations and Doppler frequency changes is poor. However, it is found that rapid geomagnetic variations such as sudden impulses and pi 2 micropulsations accompany a Doppler frequency change with a high degree of probability. The correspondence between the two is activity-wise in most cases. Peak-to-peak correspondence has been observed, however, in some cases, when the Doppler frequency changes amount to a few tenths of a c.p.s. for magnetic variations of unit strength (1γ in the south–north component). The coincidence is also very good for sudden commencements of magnetic storms. The ratio of the main positive frequency change to the magnetic-field variation in the south–north component is about one order smaller than that for the above-mentioned group. The correspondence is, in most cases, indefinite for geomagnetic bays. When a clear coincidence is seen, the ratio of the change of frequency to magnetic variation is of the order of a few hundredths of a c.p.s. per γ.