Spectral fluctuation analysis of ionospheric inhomogeneities over Brazilian territory. Part I: Equatorial F-region plasma bubbles

Abstract

In this Part I of a more general paper on the analysis of ionospheric irregularities over Brazilian territory, we apply the Detrended Fluctuation Analysis (DFA) method to evaluate in situ equatorial F-region plasma bubbles events carried out with a sounding rocket over equatorial region in Brazil. The range of scaling exponents derived from the DFA technique are compared to previous results obtained using Power Spectral Density (PSD) technique (which is widely used in this area despite its recognized inaccuracy to analyze short series). The results obtained in this first part of our investigation, using DFA, also show a wide range of spectral index variation with standard deviation of the same order found from the previous application using PSD (σm≫10%). Therefore, since the dependence of the technique are disregarded, our findings also supports that the observed lack of a universality class characterized by the nonexistence of a single spectral index (with σm≈2%) may be due to non-homogeneity energy cascades that can appear in the incoherent ionospheric turbulent process.