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@MastersThesis{Santos:2021:EsVaIo,
             abstract = "Neste trabalho apresenta-se um estudo do comportamento da 
                         ionosfera de baixas latitudes no Brasil durante a fase inicial de 
                         decl{\'{\i}}nio do ciclo solar 24 compreendendo os anos de 2016 
                         e 2017. A fase decrescente do ciclo solar {\'e} caracterizada 
                         pela redu{\c{c}}{\~a}o do n{\'u}mero de manchas solares e pelo 
                         aparecimento gradual de regi{\~o}es denominadas buracos coronais. 
                         Os buracos coronais s{\~a}o regi{\~o}es escuras, de baixa 
                         densidade e campos magn{\'e}ticos abertos, de onde emanam feixes 
                         de vento solar de alta velocidade, que ao se propagarem pelo 
                         espa{\c{c}}o interplanet{\'a}rio interagem com feixes de vento 
                         lento que os precederam criando uma regi{\~a}o de 
                         intera{\c{c}}{\~a}o de feixes. Como os buracos corrotam com o 
                         Sol, as vezes retornando em v{\'a}rias rota{\c{c}}{\~o}es 
                         seguintes, tais regi{\~o}es s{\~a}o denominadas Regi{\~o}es de 
                         Intera{\c{c}}{\~a}o Corrotante, ou CIRs (acr{\^o}nimo do 
                         ingl{\^e}s, Corotating Interaction Regions). As CIRs se 
                         caracterizam por regi{\~o}es de compress{\~a}o e 
                         rarefa{\c{c}}{\~a}o do plasma, por campos magn{\'e}ticos 
                         altamente oscilat{\'o}rios, devido a presen{\c{c}}a de ondas de 
                         Alfv{\'e}n. Estes campos s{\~a}o os respons{\'a}veis por 
                         tempestades geomagn{\'e}ticas quando sua componente sul se 
                         reconecta com o campo geomagn{\'e}tico. Estas tempestades variam 
                         na maioria das vezes entre fracas e moderadas, com poucos casos em 
                         que a tempestade {\'e} intensa. As tempestades geomagn{\'e}ticas 
                         associadas a este tipo de fen{\^o}meno, as quais s{\~a}o 
                         estudadas nesse trabalho, afetam a ionosfera de baixas latitudes 
                         de v{\'a}rias formas. Uma delas {\'e} a varia{\c{c}}{\~a}o do 
                         Conte{\'u}do Eletr{\^o}nico Total Vertical, ou VTEC 
                         (acr{\^o}nimo do ingl{\^e}s, Vertical Total Electron Content) 
                         por v{\'a}rios dias ap{\'o}s o in{\'{\i}}cio da tempestade, 
                         com intensifica{\c{c}}{\~o}es percentuais com 
                         rela{\c{c}}{\~a}o aos cinco dias mais calmos t{\~a}o elevadas 
                         quanto 400%, especialmente no per{\'{\i}}odo noturno. As causas 
                         desta intensifica{\c{c}}{\~a}o s{\~a}o discutidas em termos de 
                         campos el{\'e}tricos de penetra{\c{c}}{\~a}o, do 
                         d{\'{\i}}namo perturbado e a poss{\'{\i}}vel 
                         modifica{\c{c}}{\~a}o da atmosfera neutra. Al{\'e}m disto, 
                         verifica-se a ocorr{\^e}ncia de irregularidades de plasma na 
                         regi{\~a}o equatorial, denominadas Bolhas de plasma, ou spread-F 
                         equatorial, o que pode ter sido influenciado por campos 
                         el{\'e}tricos perturbados associados {\`a}s tempestades. 
                         Tamb{\'e}m foi realizado um estudo estat{\'{\i}}stico da 
                         resposta ionosf{\'e}rica no per{\'{\i}}odo mencionado, 
                         atrav{\'e}s do VTEC, considerando-se majoritariamente as 
                         tempestades moderadas, ou seja, utilizamos um filtro para o 
                         |Sym-H|, onde: 50 nT \≤ |Sym-H| \≤ 110 nT e para 
                         tempestades causadas apenas por CIRs/HSSs. As 
                         varia{\c{c}}{\~o}es do VTEC em quatro esta{\c{c}}{\~o}es mais 
                         representativas foram analisadas e verificou-se que as maiores 
                         intensifica{\c{c}}{\~o}es ocorrem no per{\'{\i}}odo entre 
                         18:00 e 04:00 LT (hora local), principalmente nas regi{\~o}es das 
                         cristas da Anomalia Equatorial de Ioniza{\c{c}}{\~a}o, ou EIA 
                         (acr{\^o}nimo do ingl{\^e}s, Equatorial Ionization Anomaly). 
                         Este trabalho tem, portanto, potencial para contribuir com um 
                         melhor entendimento sobre a influ{\^e}ncia do vento solar na 
                         ionosfera de baixas latitudes, durante per{\'{\i}}odos de 
                         atividade solar moderada bem como contribuir no desenvolvimento de 
                         m{\'e}todos para previs{\~a}o de Clima Espacial. ABSTRACT: This 
                         work presents a study of the behavior of the low latitude 
                         ionosphere in Brazil during the descending phase of the solar 
                         cycle 24 comprising the years 2016 and 2017. The descending phase 
                         of the solar cycle is characterized by the decreasing number of 
                         sunspots and the gradual appearance of regions defined as Coronal 
                         Holes. Coronal Holes are dark regions of low-density and open 
                         magnetic fields, from which High-Speed Solar Wind streams emanate. 
                         As the solar wind streams propagate through interplanetary space, 
                         they interact with slow wind streams that preceded them, creating 
                         interaction regions. As the Coronal Holes corotate with the Sun, 
                         sometimes returning for several subsequent rotations, as such 
                         regions are defined as Corotating Interaction Regions or CIRs. 
                         CIRs are characterized by regions of compression and rarefaction 
                         of the plasma, and highly oscillatory magnetic fields, due to the 
                         presence of Alfv{\'e}n waves. These fields are responsible for 
                         geomagnetic storms after complex reconnection processes with the 
                         geomagnetic field. These storms are usually weak to moderate with 
                         few cases of intense storms. Geomagnetic storms associated with 
                         this kind of solar events affect the low latitude ionosphere in 
                         several ways. For instance, its observed a variation of the 
                         Vertical Total Electron Content, VTEC, by several days after the 
                         storm beginning, with intensifications as high as 400% in 
                         comparison to the five quietest days VTEC, especially at night. 
                         The sources of these intensifications are discussed in terms of 
                         Prompt Penetration Electric Fields, PPEF, Disturbance Dynamo 
                         Electric Fields, DDEF, and the possible modifications of the 
                         neutral atmosphere. Also, there occur plasma irregularities over 
                         the equatorial region, defined as Equatorial Plasma Bubbles, EPBs, 
                         or Spread-Fs, which can be influenced by disturbed electric fields 
                         associated with storms. A statistical study of the ionospheric 
                         response using the parameter VTEC, was also carried out for the 
                         analyzed period, considering mostly moderate storms, that is, we 
                         use a filter for | Sym-H |, where: 50 nT \≤ | Sym-H | 
                         \≤ 110 nT only for CIRs/HSSs driven storms. The variation 
                         of the VTEC in four most representative sites was analyzed, and it 
                         was found that the highest intensifications occur in the period 
                         between 06:00 pm and 04:00 am LT (Local Time), mainly around the 
                         regions at the crests of Equatorial Ionization Anomaly, EIA. In 
                         this context, this work is of great interest for understanding the 
                         influence of the solar wind on the low latitude ionosphere during 
                         periods of moderate to low solar activity, as well as in the 
                         development or improvement of methods for Space Weather 
                         forecasting studies.",
                pages = "148",
              address = "S{\~a}o Jos{\'e} dos Campos",
           targetfile = "publicacao.pdf",
                month = "2020-05-26",
                title = "Estudo da variabilidade ionosf{\'e}rica de baixas latitudes no 
                         setor brasileiro durante eventos de feixes de vento solar de alta 
                         velocidade",
             language = "pt",
         englishtitle = "Study of low latitude ionspheric variability over brazilian sector 
                         during high speed solar wind streams events",
                 year = "2021",
                  ibi = "8JMKD3MGP3W34R/42FDKFE",
                  url = "http://urlib.net/ibi/8JMKD3MGP3W34R/42FDKFE",
               author = "Santos, Stella Pires de Moraes",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
             keywords = "ionosfera, feixe r{\'a}pido de vento solar, regi{\~a}o de 
                         intera{\c{c}}{\~a}o corrotante, tempestade geomagn{\'e}tica, 
                         conte{\'u}do eletr{\^o}nico total, ionosphere, high-speed solar 
                         wind streams, corotating interaction region, geomagnetic storm, 
                         total electron content.",
            committee = "Dal Lago, Alisson (presidente) and C{\^a}ndido, Cl{\'a}udia 
                         Maria Nicoli (orientadora) and Guedes, F{\'a}bio Becker 
                         (orientador) and Souza, Jonas Rodrigues de and Borges, Renato 
                         Alves",
        urlaccessdate = "05 out. 2022"
}


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