Characteristic U-shaped traces (cusps) on ionograms have been identified as off-angle echoes from sloping electron density contours caused by the presence of traveling ionospheric disturbances (TIDs). Temporal evolution of the cusps is associated with horizontal drift of the disturbances. A potential for reducing calculation time in numerical synthesis of vertical ionograms is under discussion. Since numerical ray tracing is computationally intensive, we have developed simplified formulation for this study. The suggested model of compound parabolic layer allows us to analytically calculate ray paths. Changes in the shape of the ionogram cusp caused by varying TID characteristics are examined.
Ionosphere, Vertical sounding, Ionogram
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