Contribuição ao estudo de distúrbios ionosféricos utilizando a técnica de VLF

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dc.contributor.advisorRaulin, Jean Pierrept_BR
dc.contributor.advisor1Latteshttp://lattes.cnpq.br/7545420353833730por
dc.contributor.authorCruz, Edith Liliana Macotelapt_BR
dc.creator.Latteshttp://lattes.cnpq.br/6670622061047166por
dc.date.accessioned2016-03-15T19:35:50Z
dc.date.accessioned2020-05-28T18:06:59Z
dc.date.available2015-04-28pt_BR
dc.date.available2020-05-28T18:06:59Z
dc.date.issued2015-03-09pt_BR
dc.description.abstractThe Earth-Low ionosphere system behaves as a waveguide for the propagation of radio waves of very low frequency (VLF). If in this system the electrical conductivity of its boundaries is perturbed, the propagation of the VLF waves will also be perturbed. There is a diversity of transient physical phenomena that are able to alter significantly the electrical conductivity of the lower ionosphere. The disturbance in this region is able to produce phase and amplitude variations with respect to a quiescent level of these waves. The aim of the present work is to study the response of the lower ionosphere to phenomena originated in the Earth, our solar system or even much farther away. For this purpose, VLF data obtained by SAVNET (South American VLF Network) during the solar cycle 24 was used. It was found that the correction by both the length of the path illuminated by the flare and the reference height coefficient allows normalizing the effect of ionospheric disturbances observed in the VLF phase signals that propagated along trajectories with a north-south or west-east direction, separately. The lower limit of detection for disturbances caused by the X-ray radiation excess is 1.8×10−9 Jm-2 and 2.6×10−7 Jm-2 for the nighttime and daytime lower ionosphere, respectively. Changes in the periodicities of the VLF signal, in the infrasonic band, were observed between 6 and 14 days prior to the seismic events, of magnitude 7, occurred in Haiti in 2010 and in Peru in 2011. Increases in the periodicities of the order of few minutes were observed when the shadow of the total solar eclipse of 2010 was moving on the Earth. Due to the solar eclipse the ionospheric reference height increased in ~3 km and the electron density decreased in 60 % of its quiescent level. Finally, it was found that the effective recombination coefficient, for 80 km height, was 1.1×10−5 cm-3s-1 during the time of the eclipse, which is an intermediate value between the diurnal and nocturnal conditions.eng
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológicopt_BR
dc.formatapplication/pdfpor
dc.identifier.citationCRUZ, Edith Liliana Macotela. Contribuição ao estudo de distúrbios ionosféricos utilizando a técnica de VLF. 2015. 76 f. Dissertação (Mestrado em Engenharia) - Universidade Presbiteriana Mackenzie, São Paulo, 2015.por
dc.identifier.urihttp://dspace.mackenzie.br/handle/10899/24123
dc.languageporpor
dc.publisherUniversidade Presbiteriana Mackenziepor
dc.rightsAcesso Abertopor
dc.subjecttécnica de VLFpor
dc.subjectbaixa ionosferapor
dc.subjectcondutividade elétricapor
dc.subjectperturbações ionosféricaspor
dc.subjectVLF techniqueeng
dc.subjectlower ionosphereeng
dc.subjectelectric conductivityeng
dc.subjectionospheric disturbanceseng
dc.subject.cnpqCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIASpor
dc.thumbnail.urlhttp://tede.mackenzie.br/jspui/retrieve/3545/EDITH%20LILIANA%20MACOTELA.pdf.jpg*
dc.titleContribuição ao estudo de distúrbios ionosféricos utilizando a técnica de VLFpor
dc.typeDissertaçãopor
local.contributor.board1Correia, Emiliapt_BR
local.contributor.board1Latteshttp://lattes.cnpq.br/1272123236892781por
local.contributor.board2Bertoni, Fernando Celso Perinpt_BR
local.contributor.board2LattesBERTONI, F. C. P.por
local.publisher.countryBRpor
local.publisher.departmentEngenhariapor
local.publisher.initialsUPMpor
local.publisher.programCiências e Aplicações Geoespaciaispor
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