This study analyses the ionospheric scintillations over the Brazilian territory, focusing on their magnitude, seasonality, and impact on Global Navigation Satellite Systems (GNSS) signal quality, specifically GPS (Global Positioning System), GLONASS (Global'naya Navigatsionnaya Sputnikovaya Sistema / Global Navigation Satellite Systems) and GALILEO. The main objective is to quantify and evaluate how such phenomena affect positioning integrity by establishing relationships between scintillation intensity, expressed by the S4 index, and signal loss events (Loss of Lock). Additionally, a statistical and temporal analysis of satellite availability per hour for different GNSS constellations is conducted, assessing their variability and reliability. Data are obtained using the ISMR (Ionospheric Scintillation Monitor Receivers) Query Tool platform, which provides information from several GNSS stations over Brazil. The analysis was carried out using SQL queries and a MATLAB-developed algorithm. The results contribute to a better understanding of ionospheric behavior in tropical regions and aim to improve GNSS-based applications, especially in environments subject to signal degradation. A significant correlation was observed between scintillation intensity and periods of high solar activity, particularly in 2014. Furthermore, although most loss of lock events were expected during strong scintillation, approximately 83% occurred during low S4 index intervals (< 0.29), suggesting other contributing factors or limitations in S4 data availability during signal interruptions.