Detalhes do Artigo
[304809] Observation of the evolution of the 25th solar cycle by measuring the ionospheric delay using the P3 method in southeastern Brazil
Autores: Fábio Kei Yamada, Luiz Vicente Gomes Tarelho, Mauro Vieira de Lima
Resumo: The ionosphere is considered the most harmful layer of the Earth’s atmosphere for the electromagnetic signals of the Global Navigation Satellite System (GNSS). Ionospheric refraction generates time delay and signal fading in the electromagnetic signals, which can cause errors in the receiver. These errors can range from a few meters to total signal unavailability, depending on the ionization level of the ionosphere plasma. This ionization is mainly affected by the intensity of solar radiation and the Earth’s magnetic field. The parameter to evaluate the behaviour of the ionosphere is the Total Electron Content (TEC). Knowing the value of TEC, it is possible to predict the effects of ionospheric refraction and develop techniques to increase reliability in services that depend on GNSS. This article will present the relationship between the evolution of the number of sunspots of the 25th solar cycle and the TEC measurement made by a geodetic receiver in the city of Xerém (RJ). We applied the P3 method of time and frequency transfer to the observables of the receiver, which allowed to detect and correct up to 90 % of the ionospheric effect. The atomic clock connected to the receiver is used in the realization of the Universal Time Coordinated (UTC). Periods related to the year’s seasons (summer and winter) were analysed since the beginning of the 25th solar cycle in 2019. Initially, the ionospheric delay is calculated, then the respective TEC is obtained. The TEC analysis characterizes the behaviour of the ionosphere caused by the daily, annual, summer, and winter variations in the incidence of solar radiation in southeastern Brazil. Therefore, the analysis can correlate the ionospheric fluctuation with the number of monthly sunspots, referring to the evolution of the 25th solar cycle. The findings of this study are expected to contribute to further developments of a deeper understanding of the ionosphere’s dynamics and further advancements in GNSS-related services.