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de Abreu, A. J.
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- PublicationOpen AccessLow-latitude equinoctial spread-F occurrence at different longitude sectors under low solar activity(2013-02-05)
; ; ; ; ; ; ; ; ; ; ; ; ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Abadi, P.; Division of Ionosphere and Telecommunication, Space Science Center, Indonesian National Institute of Aeronautics and Space (LAPAN), Indonesia ;A.J. de Abreu, A. J.; Universidade do Vale do Paraíba, São José dos Campos, Brazil ;de Jesus, R.; Universidade do Vale do Paraíba, São José dos Campos, Brazil ;Fagundes, P. R.; Universidade do Vale do Paraíba, São José dos Campos, Brazil ;Supnithi, P.; Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang (KMITL), Bangkok 10520, Thailand ;Rungraengwajiake, S.; Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang (KMITL), Bangkok 10520, Thailand ;Nagatsuma, T.; Space Weather and Environment Informatics Laboratory, National Institute of Information and Communications Technology, Tokyo 184-8795, Japan ;Tsugawa, T.; Space Weather and Environment Informatics Laboratory, National Institute of Information and Communications Technology, Tokyo 184-8795, Japan ;Cabrera, M. A.; Laboratorio de Telecomunicaciones, DEEC, FACET, Universidad Nacional de Tucumán, Tucumán, Argentina ;Ezquer, R. G.; Laboratorio de Ionósfera, Departamento de Física, FACET, Universidad Nacional de Tucumán, Tucumán, Argentina; ; ; ; ; ;; ; ; ; ; We present the results of a comparative study of spread-F signatures over five low-latitude sites: Chiangmai (CGM; 18.8 N, 98.9 E, mag. Lat. 8.8 N), Thailand; Tanjungsari(TNJ; 6.9 S, 107.6 E, mag. Lat. 16.9 S), Indonesia; Palmas (PAL; 10.2 S, 311.8 E, mag. Lat. 0.9 S) and São José Dos Campos (SJC; 23.2 S, 314.1 E, mag. Lat. 14.0 S), Brazil; and Tucumán (TUC; 26.9 S, 294.6 E, mag. Lat. 16.8 S), Argentina. The investigation was based on simultaneous ionograms recorded by an FMCW (frequency modulated continuous-wave) at CGM, an IPS-71 (digital ionosonde from KEL aerospace) at TNJ, a CADI (Canadian Advanced Digital Ionosonde) at PAL and SJC, and an AIS-INGV (Advanced Ionospheric Sounder – Istituto Nazionale di Geofisica e Vulcanologia) at TUC, during the equinoctial periods March–April (R12 = 2.0 and R12 = 2.2) and September–October (R12 = 6.1 and R12 = 7.0) 2009, for very low solar activity. Spread-F signatures were categorized into two types: the range spread-F (RSF) and the frequency spread-F (FSF). The study confirms that the dynamics and the physical processes responsible for these phenomena are actually complicated. In fact, the features that arise from the investigation are different, depending on both the longitude sector and on the hemisphere. For instance, TUC, under the southern crest of the ionospheric equatorial ionization anomaly (EIA), shows a predominance of RSF signatures, while both SJC, under the southern crest of EIA but in a different longitude sector, and CGM, under the northern crest of EIA, show a predominance of FSF signatures. Moreover, the spread-F occurrence over the longitude sector that includes CGM and TNJ is significantly lower than the spread-F occurrence over the longitude sector of PAL, SJC, and TUC.675 223 - PublicationRestrictedIonospheric disturbances in a large area of the terrestrial globe by two strong solar flares of September 6, 2017, the strongest space weather events in the last decade(2020-07)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; On September 6, 2017, the solar active region AR 2673 emitted two solar flares: the first at 08:57 UT (X2.2) and the second at 11:53 UT (X9.3); both were powerful enough to black-out high and low frequency radio waves (where UT is universal time). The X9.3 was the strongest solar flare event in the past decade. In this study, we took the advantage of these two extreme flare events to investigate corresponding effects on the ionosphere using multi-instrument observations from magnetometers, Global Positioning System – Total Electron content (GPS-TEC) receivers, ionosondes and Swarm satellites over a large geographical extent covering South American, African and European sectors. During the X2.2 flare, European and African sectors were sunlit and during X9.3 European, African, and South American sectors were sunlit and exposed to the solar flare radiation. During the X2.2 flare, there was an ionosonde blackout for a duration of about 45 min, while during the X9.3 flare this blackout lasted for 1 h and 30 min. The blackout are seen over a large global extent which demonstrates the severity of solar flare events in disrupting the radio communication. The horizontal component of Earth’s geomagnetic field has shown ripples and enhancements during these flare events. The ionospheric Vertical Total Electron Content (VTEC) showed a positive phase along with an intensification of the Equatorial Ionization Anomaly (EIA) over the South American and African sectors. The dynamical and physical processes associated with the TEC and EIA variabilities due to solar flare are discussed.217 4 - PublicationOpen AccessIonospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector(2015)
; ; ; ; ; ; ; ; ; ;Fagundes, P. R.; Universidade do Vale do Paraíba (UNIVAP) ;Goncharenko, L. P.; Massachusetts Institute of Technology ;de Abreu, A. J.; Universidade do Vale do Paraíba (UNIVAP) ;Venkatesh, K.; Universidade do Vale do Paraíba (UNIVAP) ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;de Jesus, R.; Universidade do Vale do Paraíba (UNIVAP) ;Gende, M.; Universidad Nacional de La Plata ;Coster, A. J.; Massachusetts Institute of Technology ;Pillat, V. G.; Universidade do Vale do Paraíba (UNIVAP) ;; ; ; ; ; ; ; The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major sudden stratospheric warming (SSW) event, which took place during January–February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8°N to 53.8°S, longitudes from 36.7°W to 67.8°W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSWtemperature peak. Using one GPS station located at Rio Grande (53.8°S, 67.8°W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.419 281