Navegando por Autor "Anoruo, Chukwuma Moses"

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    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 Silva
    Between 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.
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    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, Francisco
    A 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.
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    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 de
    In 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.