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Item New Findings of the Sporadic E (Es) Layer Development Around the Magnetic Equator During a High-Speed Solar (HSS) Wind Stream Event(Advancing Earth and Space Sciences) Resende, Laysa Cristina Araújo; Zhu, Y.; Denardini, Clezio Marcos; Batista, Inez Staciarini; Shi, Jiankui; Moro, Juliano; Chen, Sony Su; Santos, Fredson Conceição; Silva, Ligia Alves da; Andrioli, Vania Fatima; Muella, Marcio Tadeu de Assis Honorato; Fagundes, Paulo Roberto; Carrasco, Alexander Jose; Pillat, Valdir Gil; Wang, Chi; Liu, Z.The equatorial (Esq) and blanketing (Esb) sporadic (Es) layers occur due to the EquatorialElectrojet Current (EEJ) plasma instabilities and tidal wind components, respectively. Both Esq and Esb layers can appear concurrently over some Brazilian equatorial regions due to the peculiar geomagnetic field configuration in this sector. Previous works indicate that the inclination angle limit for the Esq occurrence in ionograms is 7°. However, we found evidence that regions more distant can also experience such equatorial dynamics during disturbed periods. In this context, we deeply investigated this EEJ influence expansion effect by analyzing the Esq layers in regions not so close to the magnetic equator during a high-speed solar wind stream event that occurred on May 05 and 06, 2018. To explain these atypical Esq layer occurrences, we considered the Es layer parameters obtained from digital ionosondes over the Brazilian regions, São Luís (dip: 9.5°), and Araguatins (dip: 10.5°). We use magnetometer data and a model named MIRE (E Region Ionospheric Model) to validate this mechanism. The results show that the eastward electric field of the Gradient Drift instability in the EEJ is effective during the magnetic storm main phase in the boundary equatorial magnetic sites, creating the Es q layers. Thus, the EEJ plasma irregularity superimposes the wind shear mechanism, changing the Es layer dynamics during disturbed periods over the magnetic equator boundary sites. Therefore, this work establishes new findings of the EEJ influence expansion dynamics in the Es layer formation over the Brazilian regions, which was considered in MIRE for the first time.Item Simultaneous occurrence of midlatitude plasma bubbles and LSTIDs during the 10 October 2024 geomagnetic storm(Elsevier) Picanço, Giorgio Arlan da Silva; Fagundes, Paulo Roberto; Moro, Juliano; Nogueira, Paulo Alexandre Bronzato; Muella, Marcio Tadeu de Assis Honorato; Nardini, Clezio Marcos de; Resende, Laysa Cristina Araújo; Silva, Lígia Alves da; Laranja, Sophia Rodrigues; Anoruo, Chukwuma Moses; Agyei-Yeboah, Ebenezer; Souza, Ana Lucia Christovam deIn this study, we present a multi-instrumental analysis of the extreme geomagnetic storm of October 10, 2024, focusing on the inter- action between Equatorial Plasma Bubbles (EPBs) and Large-Scale Traveling Ionospheric Disturbances (LSTIDs) over the American sector. Using Rate of Total Electron Content Index (ROTI), Total Electron Content (TEC), and Detrended Total Electron Content (DTEC) maps derived from Global Navigation Satellite System (GNSS) data, we investigated the ionospheric response to the geomag- netic storm. This analysis was complemented by far-ultraviolet airglow observations from the Global-scale Observations of the Limb and Disk (GOLD) mission, in situ electron density profiles from the Swarm satellite constellation, and ground-based ionosonde measure- ments. These multi-instrumental datasets revealed a sequence of coupled processes responsible for the generation, expansion, and mor- phological deformation of EPBs, extending well beyond their typical equatorial domain. Prompt Penetration Electric Fields (PPEFs), which led to an enhanced pre-reversal enhancement (PRE) over western South America, drove a substantial uplift of the ionospheric F-region, exceeding 700 km, and favored the development of large-scale EPBs. These structures manifested as a reversed-C-shaped plasma depletion band, confirmed by both ROTI and GOLD observations. Simultaneously, DTEC maps and keograms revealed the equatorward propagation of storm-time LSTIDs. A pronounced spatial and temporal overlap between EPB and LSTID signatures was observed at midlatitudes, especially across the western South American longitudinal sector. This interaction appears to have mod- ulated the outer structure of the EPBs, leading to asymmetric deformation and enhanced latitudinal expansion. Finally, our findings highlight the role of multiscale coupling between high-latitude and equatorial processes during geomagnetic storms and emphasize the need for integrated observations to fully characterize the dynamics of storm-induced ionospheric disturbances.Item Study of height-spread sporadic-E layers observed in the South American Magnetic Anomaly(Frontiers) Moro, Juliano; Xu, Jiyao; Bageston, Jose Valentin; Silva, Ligia Alves da; Resende, Laysa Cristina Araújo; Nardin, Clezio Marcos de; Andrioli, Vania Fatima; Santos, Angela Machado; Picanco, Giorgio Arlan da Silva; Li, Hui; Zhengkuan, Liu; Wang, Chi; Schuch, Nelson JorgeSpread echoes from the E-region observed in ionograms obtained at high latitudes are generally classified as auroral sporadic-E (Esa) layers. These layers have also been detected in nighttime ionograms collected at some ionospheric stations in the South American Magnetic Anomaly (SAMA) region in Brazil during the recovery phases of geomagnetic storms. However, similar echoes have also been observed in the SAMA during geomagnetically quiet periods or daytime, which are not caused by energetic particle precipitation. Therefore, investigating the occurrence of these spread echoes over a longer period, rather than focusing solely on case studies, has become important. Thus, this study aims to analyze the occurrences of spread echoes from the E-region, referred to here for the first time as “Height-Spread Es (HSEs) layers.” The analysis is based on Digisonde data obtained at the Santa Maria station (29.7° S, 53.8° W, ∼22.000 nT) in Brazil over 1 year (2019/2020). The study initially presents examples of these traces on ionograms and then examines their occurrence rates over several time intervals (hours, months, seasons). Among other findings, the statistical analysis reveals that the occurrence rate of HSEs layers is 9.8% during the analyzed period. The HSEs layers appeared predominantly at night and under geomagnetically quiet conditions. Most HSEs layers lasted between 1 h and 3 h 30 min, with a peak incidence during November, December, and January. Finally, the study discusses the most likely mechanisms responsible for HSEs layer formation, considering the geomagnetic conditions and time of their detection on ionograms.