Movement of the<i>F</i>-region

Abstract

In the course of a fixed-frequency ionospheric study, employing a pulse-triggered transmitter operating on 3.5 Mc/s and three spaced-receivers, the transmission delay was continuously recorded. Aside from a vertical-incidence transmission, two oblique transmissions were thus available with 62 and 109 km as base lines, the latter being correspondingly oriented in an approximate west-east and northwest-southeast direction. An analysis of the echoes from the F-region was made for the period between August 1952 and December 1953. Successive irregularities observed simultaneously on three records displayed frequently consistent time-displacements. Assuming the midpoints of the transmissions to be characteristic and preferred areas for the reflection of the h.f.-pulses, the time-displacements were interpreted as being due to a mechanical motion of the F-region. Direction and speed of this movement were thus obtained, and semiannual and annual periods of these components became apparent.