Estimating the Characteristics of Traveling Ionospheric Disturbances from Vertical Incidence Ionograms within a Compound Parabolic Layer Model

The characteristic U-shaped traces (cusps) in ionograms are associated with the passage of traveling ionospheric disturbances (TIDs), which lead to horizontal electron density gradients in the ionosphere and, therefore, to off-angle reflections in radio sounding. A new form of representation is considered for daily ionospheric sounding data. A compound parabolic layer model is proposed, which allows analytical calculation of ray paths to speed up the “homing-in” of the rays. Changes in the shape of the trace in the ionogram due to varying the TID characteristics are examined. A discussion is given of the possibilities for estimating TID characteristics from digitized vertical sounding ionograms.