Aspects of the linear and nonlinear development of equatorial spread F with application to ionospheric scintillation

A hybrid model for density irregularities is introduced which may be more physically meaningful in some wavelength regimes than the anisotropic power-law model previously proposed. Both of these irregularity models are constructed in a way consistent with in situ observations, and the weak scattering thin screen theory is applied in a mathematically rigorous way to obtain exact expressions for such parameters as the RMS fluctuation in the phase of wave front emerging from the irregularity region, the scintillation index S sub 4 (RMS fluctuation in the intensity of the received signal), and characteristic scales of scintillating spectrum. The theory is then applied to the results of density fluctuation measurements, obtained by a rocket probe during spread F occurrence.