WAVE DISTURBANCES IN THE IONOSPHERIC F2 LAYER ELECTRON DENSITY: DIURNAL AND SEASONAL VARIATIONS DURING THE DECLINING PHASE OF THE SOLAR CYCLE

Abstract

Purpose: The regular and quasi-periodic diurnal and seasonal variations in the F2 region electron density N during the declining phase of the solar cycle in 2016. Desing/methodology/approach: For the system spectral analysis of time variations N, the short-time Fourier transform, the adaptive Fourier transform, and the wavelet transform were used. Findings: The dominant oscillation occurs with a period of 150÷260 min, amplitude of ΔNa≈(0.4÷1.1)·1011 m-3, and the amplitude of ΔNa/Ñ≈0.09÷0.23 on a relative scale in the ionospheric F2 region over all seasons. This oscillation had temporal duration of 13 to 17 h, depending on the season. The amplitude of the oscillations with other periods was notably smaller. Conclusions: The regular diurnal and seasonal variations and wave disturbances in the electron density at the F2 peak height during the ascending and declining phases of the solar cycle are generally close to and completely correspond to the existing concept of physical and chemical processes in the ionosphere.

Keywords

• ionosonde
• diurnal and seasonal dependence
• electron density
• regular and quasi-periodic disturbances
• system spectral analysis
• wave disturbances