A radio wave scattering algorithm and irregularity model for scintillation predictions

Abstract

[1] An algorithm for calculations of phase and amplitude scintillation of satellite signals in the equatorial region will be described in detail. The algorithm will be developed by initially transforming the discrete version of the Huygens-Fresnel integral into a convolution involving a series of coefficients with decreasing amplitudes. Next, the Fourier transform of the corresponding series of coefficients is stored for all the frequencies of interest, and the fast Fourier transform algorithm is used to evaluate discrete convolutions. Two phase screen models will be described. The first assumes that the phase fluctuations of the wave front emerging from the bottom of the irregularity layer are proportional to electron density fluctuations directly obtained from satellite in situ measurements. The second assumes that the same phase fluctuations can be obtained from their power spectral densities and phase spectra, represented by analytical functions with parameters provided by physics-based or morphological models of ionospheric irregularities. The propagation algorithm will be applied to both phase screen models, assuming five frequencies in the high-VHF to low-SHF band (suffering strong to weak scattering), to display its potential in the prediction of phase and amplitude scintillation of satellite signals.

C/NOFS: a mission to forecast scintillations

“…Examples of this include discrete versions of the Huygens-Fresnel integrals (Costa and Basu, 2002), improved parabolic equation solvers, and sub-sampled phase screen work (Beach et al, 2002). Insights gained from each of these efforts may lead to dramatic improvements in estimation accuracy and efficiency.…”

Equatorial ionospheric zonal drift model and vertical drift statistics from UHF scintillation measurements in South America

“…First, there is the applicability of the simple geometry used here, which should be compared with a full treatment of slant propagation through a real ionosphere. For low elevation angles, however, the approximations in propagation models like Costa and Basu (2002) spaced antenna drift velocities might not reflect the ambient plasma drift during the turbulent early stage of plasma bubble development, which typically occurs before 22:00 LT. In fact, the top panels of Figs.…”

Multiple phase screen modeling of ionospheric scintillation along radio occultation raypaths

“…[7] The multiple phase screen method is an efficient numerical technique for simulating the propagation of radio waves through extended random media which allows both amplitude and phase fluctuations to accumulate within the medium [Knepp, 1983;Grimault, 1998, Béniguel, 2002Costa and Basu, 2002]. This capability is important when modeling radio occultation experiments through the ionosphere because the propagation path inside the random medium can be very long.…”