Navegando por Autor "Picanço, Giorgio Arlan da Silva"
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Item Advantages and disadvantages of VTEC, ROTI and airglow images in studying equatorial plasma bubbles(Elsevier) Souza, Ana Lucia Christovam de; Prol, Fabricio dos Santos; Muella, Marcio Tadeu de Assis Honorato; Picanço, Giorgio Arlan da Silva; Camargo, Paulo de Oliveira; Monico, João Francisco GaleraEquatorial plasma bubbles (EPBs) are large-scale plasma depletion structures, observed near the geomagnetic equator and in low- latitude regions after sunset. Several instruments have been employed to study EPBs, such as ionosondes, in situ satellites, coherent and incoherent scatter radars, airglow imagers, GNSS radio occultation, and GNSS ground-based stations. Among these instruments, Total Electron Content (TEC) and Rate of TEC change Index (ROTI) data derived by GNSS measurements are presenting as outstand- ing data sources to study the climatology of EPBs. In this study, we evaluate the reliability of TEC and ROTI index for mapping iono- spheric plasma bubble structures in comparison to airglow images, demonstrating the performance of each technique and highlighting their respective advantages and disadvantages. The results demonstrate that TEC and ROTI time series are effective to identify plasma bubble occurrence in terms of temporal profiles, horizontal maps, and keograms for EPB velocity estimation. In terms of ionospheric temporal profiles, all techniques presented a good correspondence, TEC data may present direct characteristics of plasma bubbles, i.e., the intensity of the electron density depletions, while ROTI values are more suitable to present the occurrence, or not, of plasma bubbles. TEC maps showed advantages in mapping the horizontal distributions of EPBs, specially at the equatorial regions where ROTI failed to detect disturbances. Velocity estimates based on keograms from airglow data averaged 111 m/s, while TEC and ROTI index averaged 106 m/s and 107 m/s, respectively. Overall, TEC data presented better estimates of velocities due to the geometric and physical information, while ROTI offers statistical insights that often mask the natural propagation of EPBs.Item Equatorial Ionization anomaly disturbances (EIA) triggered by the May 2024 solar Coronal Mass Ejection (CME): The strongest geomagnetic superstorm in the last two decades(Elsevier) Fagundes, Paulo Roberto; Pillat, Valdir Gil; Habarulema, John Bosco; Muella, Marcio Tadeu de Assis Honorato; Venkatesh, Kavutarapu; Abreu, Alessandro José de; Anoruo, Chukwuma Moses; Vieira, Francisco; Welyargis, Kibrom Hadush; Agyei-Yeboah, Ebenezer; Tardelli, Alexandre; Felix, Gabriela de Sousa; Picanço, Giorgio Arlan da SilvaBetween May 10–15, 2024, a geomagnetic superstorm, the most intense in the past two decades, was recorded. This G5-level super- storm exhibited a Disturbance Storm Time (Dst) index of −412 nT and a Kp index of 9. The sudden storm commencement (SSC) occurred on May 10 at 17:05 UT, followed by the main phase from 18:00 UT on May 10 to 03:00 UT on May 11. The recovery phase lasted from 03:00 UT on May 11 until May 15. During this period, nine X-class solar flares were observed, indicating intense solar activ- ity. The superstorm led to significant ionospheric disturbances, which were analyzed using data from two ionosonde stations and GPS- TEC data from a network across the American sector, covering equatorial to low-mid latitude regions. A negative storm effect was observed in the equatorial region, while a positive ionospheric effect was observed in the low-mid latitudes during the main phase, accom- panied by the uplift of the F-layer to altitudes exceeding 1024 km, driven by storm induced prompt penetration electric fields. Addition- ally, a strong negative storm effect was recorded during the recovery phase on May 11 in daytime, probably due to O/N2 ratio changes.Item Impact of CIR/HSS-Driven Geomagnetic Storm and HILDCAAs* Events on Brazilian Equatorial and Low Latitude Ionosphere(2025-10-20) Oliveira, Virgínia Klausner de; Pillat, Valdir Gil; Prestes, Alan; Picanço, Giorgio Arlan da Silva; Echer, Ezequiel; Silva, Marlos Rockenbach da; Essien, Patrick; Abaidoo, Samuel; Cândido, Claudia Maria Nicoli; São José dos CamposThis research investigates the impact of CIRs/HSS-driven geomagnetic storms and High- Intensity, Long-Duration Continuous Auroral Electrojet Activity (HILDCAA) events on the Brazilian equatorial and low-latitude ionosphere during the early descending phase of solar cycle 23, with a focus on the geomagnetic disturbance from October 12–23, 2003. Ionospheric variability was analyzed using Digisonde data from São Luís and Cachoeira Paulista, representing the equatorial region and the southern crest of the Equatorial Ionization Anomaly (EIA), respectively, along with GNSS-derived Total Electron Content (TEC) data from a latitudinal chain of stations spanning Fortaleza to Uruguaiana, Brazil. To assess ionospheric perturbations, disturbed-day values were compared with a five quiet-day (5QD) average, serving as a baseline for normal conditions. Plasma drift disturbances were examined using the Fejer-Scherliess empirical model, employing the auroral electrojet index (AE) as a key parameter. The CIR/HSS events were characterized by prolonged geomagnetic forcing, with solar wind speeds reaching ˜ 619 km/s and IMF-Bz components facilitating enhanced magnetosphere-ionosphere coupling. These storms exhibited an intense main phase (Sym-H ˜ -100 nT) and a notably extended recovery phase (˜ 8 days), during which disturbance dynamo electric fields (DDEFs) played a crucial role in ionospheric restructuring. Results indicate a strong coupling between the auroral and equatorial ionospheres, with equatorward propagating disturbance winds driving F-region uplifts and nighttime spread- F occurrences. TEC variations exhibited distinct temporal and latitudinal patterns, with enhancements predominantly observed during daytime and post-sunset hours, influenced by the interplay of penetration electric fields (PPEFs), DDEFs, and auroral-driven disturbance winds. Notably, TEC increases were prominent at the Equatorial Ionization Anomaly (EIA) crest during equinoctial months, particularly in March–April, whereas winter months exhibited minima. Analysis of thermospheric O/N2 ratios confirmed that neutral composition changes were not the primary driver of TEC variability during HILDCAA events, whereas they played a significant role during CIR/HSS-driven geomagnetic storms. Additionally, large-scale ionospheric irregularities, examined through the Rate of TEC Index (ROTI), were most pronounced from nighttime to post-midnight, peaking at the equator during equinoxes and shifting toward lower latitudes from May to August. Empirical modeling validated that disturbance-induced vertical plasma drifts modulate F-region dynamics, with significant uplifts in h’F and hmF2, alongside foF2 reductions. Comparative statistical analysis of geomagnetic, solar wind, and ionospheric parameters demonstrated that CIR/HSS-driven HILDCAA events induce persistent ionospheric perturbations, comparable to intense ICME- driven storms. These findings underscore the prolonged influence of CIR/HSS-induced geomagnetic activity on equatorial and low-latitude ionospheric behavior, contributing to a deeper understanding of space weather impacts on radio propagation and other technological systems in the near-Earth environment.Item Midnight Simultaneous Observations of Spread-F and Multiple F-Layer Stratifications During the 11-12 May 2024 Geomagnetic Superstorm(Advancing Earth and Space Sciences) Fagundes, Paulo Roberto; Pillat, Valdir Gil; Anoruo, Chukwuma Moses; Picanço, Giorgio Arlan da Silva; Pezzopane, Michael; Habarulema, John Bosco; Kavutarapu, Venkatesh; Tardelli, Alexandre; Souza, Ana Lucia Christovam de; Vieira, FranciscoA geomagnetic superstorm occurred from May 10 to 12, 2024, producing significant spatial and temporal disturbances in the ionosphere. Ground‐based ionosonde and GPS‐TEC data enabled the identification, analysis, and possible interpretation of a unique event: the simultaneous occurrence of Spread‐F and multiple F‐layer stratifications during the local midnight hours of May 11. To the best of our knowledge, this is the first documented case of such a phenomenon occurring at local midnight. This study provides new insights into the dynamics of the equatorial and low‐latitude ionosphere under extreme geomagnetic conditions and highlights the critical role of coordinated, multi‐instrument observations in advancing our understanding of ionospheric electrodynamics.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.