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Item Assessing the effects of a minor CIR‐HSS geomagnetic storm on the brazilian low‐latitude ionosphere: ground and space‐based observations(Advancing Earth and Space Sciences) Chingarandi, Frank Simbarashe; Cândido, Claudia Maria Nicoli; Guedes, Fabio Becker; Jonah, Olusegun Folarin; Santos, Stella Pires Moraes; Klausner, Virgínia; Osanyin, Taiwo OlusayoThis paper investigates the effects of a minor G1 Co-rotating Interaction Region (CIR)/High-Speed Stream (HSS)-driven geomagnetic storm that occurred on (13–14 October 2018), during deep solar minimum. We used simultaneous observations from multiple instruments, namely; ground-based Global Navigation Satellite Systems (GNSS) receivers, a Digisonde, ground magnetometers, and space-based observations from the National Aeronautics and Space Administration Global-scale Observations of Limb and Disk (GOLD) and SWARM missions. This study presents a detailed picture of the low-latitude ionosphere response over the Brazilian sector during a minor storm. Our results showed that the minor CIR/HSS-driven storm caused a positive ionospheric storm of over ∼20 TECU in magnitude. For the first time, periodic post-sunset irregularities and Equatorial Plasma Bubbles, equatorial plasma bubbles, were analyzed using GOLD FUV OI 135.6 nm emission, Total Electron Content (TEC) maps, Rate of TEC index, ROTI, and TEC gradients. Fluctuations in the interplanetary magnetic field Bz and changes in the thermospheric column density ratio (∑O/N2) are discussed as the main sources of ionospheric changes during the storm. This paper highlights the importance of monitoring and understanding the impact of Sun-Earth interactions and provides insight into the behavior of the low-latitude ionosphere during minor geomagnetic storms.Item Spatial Characteristics of GNSS Fading and Scintillation in Low Latitudes(Springer Nature Link) Di Santis, Victor; Moraes, Alison; Costa, Emanoel; Sousasantos, Jonas; Silva, Paulo Renato Pereira; Souza, Ana Lucia Christovam dePrevious studies evaluated several characteristics of ionospheric fading events and amplitude scintillation. However, a detailed analysis on how the fading profiles and scintillation probabilities vary according to the dip latitude is still required. In this work, a statistical analysis of data from four ground-based scintillation monitors was performed to evaluate how the α coefficient (first parameter of the “α–μ” probability distribution model); the deepest fading occurrence; the number of fading events per minute; and the duration of fading events change according to the dip latitudes of the ionospheric pierce points (IPPs) of transionospheric propagation paths. The results reveal a nuanced spatial variation in amplitude scintillation, emphasizing an enhanced severity within the equatorial ionization anomaly (EIA) southern crest, resulting in a clear increase in the probability of severe fading events. An increasing trend in the α fading coefficient at more poleward dip latitudes was found, in comparison with results from equatorward locations, suggesting an asymmetry favoring more severe fading events within the former region. The average fad- ing occurrences are significantly larger over the EIA peak region, especially for increasing scintillation levels. Complementary Cumulative Distribution Function (CCDF) curves demonstrate peak probabilities between dip latitudes from − 14.5° to − 10.5° for higher scintillation levels, also displaying an asymmetrical pattern around the EIA boundaries. This study provides important insights on the spatial dynamics of scintillation and fading profiles, enhancing the understanding of low-latitude ionospheric effects on global network satellite system (GNSS) signals.Item Spatial Characteristics of GNSS Fading and Scintillation in Low Latitudes(Springer Nature) Santis, Victor Di; Moraes, Alison; Costa Emanoel; Sousasantos, Jonas; Silva, Paulo Renato Pereira; Souza, Ana Lucia Christovam dePrevious studies evaluated several characteristics of ionospheric fading events and amplitude scintillation. However, a detailed analysis on how the fading profiles and scintillation probabilities vary according to the dip latitude is still required. In this work, a statistical analysis of data from four ground-based scintillation monitors was performed to evaluate how the alpha coefficient (first parameter of the "alpha-mu" probability distribution model); the deepest fading occurrence; the number of fading events per minute; and the duration of fading events change according to the dip latitudes of the ionospheric pierce points (IPPs) of transionospheric propagation paths. The results reveal a nuanced spatial variation in amplitude scintillation, emphasizing an enhanced severity within the equatorial ionization anomaly (EIA) southern crest, resulting in a clear increase in the probability of severe fading events. An increasing trend in the alpha fading coefficient at more poleward dip latitudes was found, in comparison with results from equatorward locations, suggesting an asymmetry favoring more severe fading events within the former region. The average fading occurrences are significantly larger over the EIA peak region, especially for increasing scintillation levels. Complementary Cumulative Distribution Function (CCDF) curves demonstrate peak probabilities between dip latitudes from - 14.5 degrees to - 10.5 degrees for higher scintillation levels, also displaying an asymmetrical pattern around the EIA boundaries. This study provides important insights on the spatial dynamics of scintillation and fading profiles, enhancing the understanding of low-latitude ionospheric effects on global network satellite system (GNSS) signals.