The Ionospheric Effects that Cnoidal Electron Density Waves Have on Decametric Radio Signals

Abstract

Numerical simulations have been made of decametric wave Doppler shift and a focusing factor due to cnoidal waves of electron concentration progressing in the terrestrial ionosphere. The solutions of the Korteweg–de Vries equation are used to model the nonlinear waves. The nonlinear wave parameters (the relative amplitude of electron concentration disturbances and the period) are determined from observations. Calculations are performed for various sounding frequencies and wave polarizations, for nighttime and daytime ionosphere models. The Doppler shift and the focusing factor are shown to be large enough to be detected. The passage of cnoidal waves gives rise to characteristic Doppler shifts and focusing factors, which permits their detection with other variations in the background.Comparisons between measurement data and calculations are presented. The main characteristics of a cnoidal wave are determined from observations.