Dispersion of ionospheric waves

Abstract

THE phase speed dispersion of travelling ionospheric disturbances (TIDs) has been measured using data from a three-dimensional array of c.w. Doppler sounders¹. Horizontal and vertical trace speeds of phase surfaces were measured as a function of wave period by performing cross-spectral analysis of the array signals. Although the measured dispersion varied considerably depending on the coherence of the wave activity across the array, the average horizontal trace speed was approximately proportional to T^−1/2, where T is the period. From a very limited set of measurements, vertical trace speed was tentatively determined as proportional to T⁻¹. Additional measurements of highly coherent waves now indicate that the vertical dispersion is even stronger than T⁻¹ at the short periods (12-25 min.).