Produção Cientifica

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https://dspace.mackenzie.br/handle/10899/33872

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Navegando Produção Cientifica por Autor "Abalde J.R."

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  • Artigo
    Ionospheric GPS-TEC responses from equatorial region to the EIA crest in the South American sector under intense space weather conditions
    de Abreu A.J.; Correia E.; Denardini C.M.; de Jesus R.; Venkatesh K.; Roberto M.; Abalde J.R.; Fagundes P.R.; Bolzan M.J.A.; Gende M. (2022)
    © 2021 Elsevier LtdWe present and discuss the ionospheric F-region observations from equator to the equatorial ionization anomaly (EIA) regions over the South American sector during an intense space weather event occurred between 27 and May 29, 2017. During this geomagnetic storm, the symmetric-H (SYM-H) reached a minimum of −142 nT at ∼0700 UT on May 28, 2017. For this investigation, we analyze the vertical total electron content (VTEC) observations from a chain of nearly 120 Global Positioning System (GPS) stations. Magnetometer measurements obtained at two stations in the low latitude regions are also presented. The observations do not indicate prompt penetration electric field (PPEF) effects in the VTEC variations. Magnetometer's observations over Cuiabá (CBA) and Cachoeira Paulista (CXP) in central west and south parts of Brazil, respectively, have shown a strong cross-correlation with SYM-H in the period between 3 and 48 h. The results also show positive ionospheric storm phase during the recovery phase on May 28, 2017. Positive effect during the recovery phase of the geomagnetic storm is possibly associated with effects of disturbances winds. During the recovery phase, a strong intensification of the EIA took place, possibly related to an additional ionization effect. The VTEC values show differences between the west and east sectors. This indicates that the EIA crest is stronger in the east sector than in the west sector, possibly due to the combination of disturbance wind effects and geomagnetic field geometry where in the east sector the field lines are more inclined.
  • Artigo
    Observation and simulation studies of ionospheric F-region in the South American and Antarctic sectors in the intense geomagnetic storm of August 2018
    de Abreu A.J.; Correia E.; Jonah O.F.; Venkatesh K.; Thomas E.G.; de Jesus R.; Roberto M.; Abalde J.R.; Fagundes P.R. (2025)
    © 2024 Elsevier LtdIn this investigation, we present and discuss the ionospheric F region observations in the equatorial, low-, mid-, and near high-latitude regions in the South American and Antarctic sectors during the intense geomagnetic storm that occurred on 25–27 August 2018. The geomagnetic storm reached a minimum Dst of −175 nT at ∼0700 UT on 26 August. We present the variations of vertical total electron content (VTEC) from a chain of almost 200 GPS stations, covering the South American and Antarctic sectors. A comparison with model simulations from the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM) is realized. The results obtained show that during the main phase of the storm, a southward Bz component of the interplanetary magnetic field (IMF) and an eastward prompt penetration electric field (PPEF) can be observed, but they had no significant impact on the ionospheric plasma. A long recovery phase a predominance of positive phase is observed during daytime. The observations show the effects of an unusual case of multiple PPEF, occurred on 26 August, and effects of thermospheric winds disturbances, occurred on 27 August, resulting in increased VTEC values on both days. The TIE-GCM model reproduces the VTEC increases during the main and recovery phases from mid-latitudes to the equatorial region, but it underestimates the observed values near high-latitudes.