The Phase Speed of a Travelling Disturbance in the F Region of the Ionosphere and its Comparison with Group Velocity

Abstract

Three methods of measuring the phase speed of a disturbance in the F region, that is, the speed of a peak or trough in the isoionic contours, are given using ionograms records from one station. The analysis has been applied to one such disturbance whose group velocity was known to be 10 km/min. All three methods gave the phase speed to be about half of this. The theoretical explanation of this observation is discussed.