Abstract

Among the civil applications the critical point is the aeronautical use of satellite-based navigation. No other civilian application has as many standards and safety criteria involved as aviation. The area of civil aviation is one of the main beneficiaries with the use of GPS. The use of GPS for air navigation enables a greater concentration of aircraft in an assured space, since the position of the aircraft is known with certain precision. This information makes it possible to optimize routes, save fuel, and manage air traffic more efficiently. The ionosphere is the main factor that influences the accuracy of the positioning of users who have receivers of only one frequency like civilian aviation case. It is known that the ionosphere affects the GNSS signal in a dispersive and very dynamic way, varying according to solar activity, geographic location, hours of the day or even according to seasonality. In the Brazilian region, the ionosphere has a differently behavior due to the performance of physical phenomena that influence the ionosphere. Among the effects caused on the GNSS signals by the ionosphere, ionospheric scintillation stands out. It is one topic of great interest for investigation because it affects numerous activities that involve positioning, such as precision agriculture, air navigation, among others. Thus, due to its importance and particularity, ionospheric scintillation has been widely studied due to its effects for air navigation and augmentation systems. In this work it is presented an assessment of the statistics of scintillation over different sites in Brazil. Analyzes of variations in the occurrence of ionospheric scintillation are presented. For such analyzes, techniques were used based on the percentage of occurrence of ionospheric scintillation, both in phase and in amplitude, given a certain threshold, as well as statistical techniques. From the data from the GNSS NavAer network, between March/2011 and December/2018 it was obtained that for the amplitude ionospheric scintillation the biggest peaks occurred in the year 2013 and 2014, between 22h and 4h UTC and in the months of October to March, being November the month with the highest occurrence. As for the phase scintillation, the biggest annual peaks were also in 2013 and 2014 in the months of October to March. This research shows which areas are most susceptible to the effects of scintillation and consequently where GNSSbased aviation will be most susceptible to these effects of space weather. Considering the future of aviation in the context of modernized and multi-frequency signals, this work also evaluates different GPS frequencies. The results showed that scintillation performs strongly on GNSS signals and the L5 frequency is more affected by amplitude and phase scintillation than in L1 and L2, although the latter is also seriously affected.

Keywords

climatology, ionospheric scintillation, GNSS signals