Abreu, Alessandro José deCorreia, EmiliaJonah, Olusegun FolarinVenkatesh, KavutarapuThomas, Evan G.Jesus, Rodolfo F. deRoberto, MarisaAbalde, José RicardoFagundes, Paulo Roberto2025-08-192025-08-19https://repositorio.univap.br/handle/123456789/1028In 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 ob- tained 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.PDFen-USObservation and simulation studies of ionospheric F-region in the South American and Antarctic sectors in the intense geomagnetic storm of August 2018Artigos de PeriódicosJournal of Atmospheric and Solar-Terrestrial Physics10.1016/j.jastp.2024.106394IonosphericF-regionGeomagnetic stormABREU, Alessandro José de et al. Observation and simulation studies of ionospheric F-region in the South American and Antarctic sectors in the intense geomagnetic storm of August 2018. Journal of Atmospheric and Solar-Terrestrial Physics, v. 266, p. 1-18, 2025. Disponível em: 10.1016/j.jastp.2024.106394.Universidade do Vale do ParaíbaInstituto Nacional de Pesquisas EspaciaisInstituto Tecnológico de AeronáuticaUniversidade Presbiteriana MackenzieInternational Geospace GroupNational Atmospheric Research LaboratoryDartmouth College