Algoritmo análise de pico a pico positivo para detecção de irregularidades ionosféricas com dados de satélites C/NOFS E GPS

Abstract

It is known that the ionosphere may exhibit irregularities, which are perturbations in ionospheric plasma density, and that they induce considerable noise levels and signal failure in telecommunications systems and in global navigation and positioning systems. Also called ionospheric bubbles or ionospheric plasma depletions, which are generated by the Rayleigh-Taylor Instability. The term plasma depletion is often used when the detection of irregularity is by means of instruments on board satellites, consisting of a reduction of plasma abruptness followed by a subsequent recovery to a value close to the previous reduction. This work presents an algorithm developed for the detection of ionospheric plasma depletion, which is used for a study of the electrodynamics of the low latitude equatorial ionosphere. The algorithm uses data from the PLP (Planar Langmuir Probe) instrument on the C/NOFS (Communications/Navigation Outage Forecasting System) satellite and receivers on GPS (Global Positioning System). For this, TEC (Total Electron Content) data of the GPS networks scattered in South America and in situ density of the satellite C/NOFS, together with geomagnetic parameters are available. The algorithm first extracts the variations of electronic density (for PLP - C/NOFS data) or variations of the TEC (for GPS receiver data), which are filtered through Band Pass Filter (BPF) and Fast Fourier Transform (FFT). The result of the filtering are oscillations, which are analyzed by the algorithm by measuring the distances of each positive peak of the oscillations at all subsequent peaks. The algorithm presents good computational cost, capable of detecting plasma depletions with PLP-C/NOFS data and GPS receivers. Using 182 GPS receiver stations located on the South American continent, a study of the day-today variability of ionospheric irregularities was carried out, as well as the study of the seasonality of the irregularities in January 2010, thus showing the validation and feasibility of the algorithm. In order to emphasize the validity of the algorithm, we present ionograms referring to the digissondas of Fortaleza and São Luís. The calculations of the execution time measure of the algorithm are exposed, so it is possible to measure its efficiency for comparison with other algorithms.