Intensity scintillation parameters for characterizing transionospheric radio signals

The structure of intensity scintillation is characterized by the fourth-order complex signal moment Γ₄. The differential equation that governs the behavior of Γ₄ is written in terms of dimensionless variables to isolate parameters that can be inferred from intensity scintillation data without a priori knowledge of scale sizes, layer thickness, propagation angles, etc. It is shown, for example, that when the outer scale is large compared to the Fresnel radius, the scintillation index measured under weak scatter conditions can be used to derive a universal scintillation index curve. Multifrequency scintillation data are presented to demonstrate the concept.