Caracterização do comportamento da ionosfera durante eventos " magnetic crochets"

• Autor(a) principal: Almeida, Alexandre Rodel de
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: http://dspace.mackenzie.br/handle/10899/24135
• topic: ionosfera; flares solares; magnetic crochet; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOFISICA::AERONOMIA

In the present work a statistical study involving medium and high intensity solar flares occurred between 2011 and 2015, in the diurnal period, in the Brazilian territory is presented. This statistic provides important information about the flares associated with rare events called "magnetic crochets", which are variations in the horizontal component of the surfacial geomagnetic field associated with the electromagnetic radiation of the Sun. For a better understanding of these phenomena and for the characterization of the behavior of the ionosphere during the "magnetic crochets", some examples are shown in which ionospheric, solar and geomagnetic parameters are compared. This type of analysis is infrequent nowadays and the literature does not present studies with such characteristics in the region of South America involving ionospheric soundings. The results show a good correlation between more intense X-ray and H-alpha explosions originating in active regions with more complex magnetic structures near the central meridian on the solar disk, which occurred around 15:00 UT (~ 12:00 local time Time), with a considerable number of "crochets". The results also show variations in the horizontal component of the atipically high surfacial geomagnetic field at stations around 22 ° south latitude, while in other regions of the globe the variations in this latitude range are smaller than in the equatorial regions, suggesting anomaly's influence in this region of South America. Results of the analysis related to the low ionosphere showed a good correlation between the more impulsive and intense events in the X-ray range of 0.4 to 1 Angstrom, with modification in the height of reflection of the signal in (VLF) and conductivity change at the ionosphere's base, which may suggest a characteristic of flares associated with magnetic crochets.