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@PhDThesis{Adhikari:2015:HIEfRe,
               author = "Adhikari, Binod",
                title = "HILDCAA-related effects recorded in middle-low latitude 
                         magnetometers",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2015",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2015-02-24",
             keywords = "HILDCAA, geomagnetic storm, geomagnetic substorm, space 
                         electrodynamics, magnetosphere, tempestade geomagn{\'e}tica, 
                         subtempestade geomagn{\'e}tica, eletrodin{\^a}mica espacial, 
                         magnetosfera.",
             abstract = "Disturbances of the geomagnetic field are caused by enhanced solar 
                         windmagnetosphere electrodynamical coupling process. The principal 
                         cause of geomagnetic disturbance is the magnetic reconnection 
                         between the southward directed interplanetary magnetic field 
                         component and the northward directed magnetopause field, that 
                         establishes an electrodynamic coupling between the solar wind 
                         plasma and magnetosphere. In general, this coupling is controled 
                         by dominant structures emanating from the sun like sporadic 
                         coronal mass ejections (CMEs) and their interplanetary 
                         counterparts (ICMEs), around the solar maximum, and by corotating 
                         high-speed streams, including corotating interaction region (CIR), 
                         in the descending and minimum phases of solar cycle. These high 
                         speed streams are embedded with highly fluctuating Alfven waves, 
                         which produce phenomena called HILDCAA events (high-intensity, 
                         long duration, continuous AE activity). This study investigates 
                         magnetic records from middle-low latitude geomagnetic 
                         observatories during HILDCAA periods. To this purpose, three 
                         primary conditions of the interplanetary space are considered: 
                         HILDCAA (i) not preceded by magnetic storm, (ii) preceded by storm 
                         generated by CIR, and (iii) preceded by storm generated by ICME. A 
                         fourth case is considered as a background condition: a 
                         geomagnetically quiet interval. As methodology of analysis, 
                         wavelet techniques to study multi-scale features of the HILDCAA 
                         events were explored in this work. The signal analyses techniques 
                         are composed by continuous wavelet transform, discrete wavelet 
                         transform, cross correlation using wavelet, and the usual modulus 
                         cross correlation. Complementarly, an evaluation on the field 
                         aligned currents (FAC) are considered in the investigation. 
                         Besides this, we estimate the polar cap potential (PCP) and 
                         merging electric field (Ey), and examine the role of PCP and 
                         geomagnetic AL index to monitor geomagnetic activity generated by 
                         geoeffective solar wind parameters during HILDCAAs. Thus, this 
                         work contributes to extend the understanding of HILDCAA events at 
                         higher latitudes to disturbances occurring at middle-low 
                         latitudes. There are magnetic effects related to the occurrence of 
                         HILDCAA even at middle-low latitudes. RESUMO: 
                         Perturba{\c{c}}{\~o}es do campo magn{\'e}tico da Terra s{\~a}o 
                         causadas por intensifica{\c{c}}{\~a}o de um processo de 
                         acoplamento eletrodin{\^a}mico entre o vento solar e a 
                         magnetosfera. A causa principal das perturba{\c{c}}{\~o}es 
                         geomagn{\'e}ticas {\'e} a reconex{\~a}o magn{\'e}tica entre o 
                         campo magn{\'e}tico interplanet{\'a}rio com 
                         orienta{\c{c}}{\~a}o para o sul e o campo magn{\'e}tico da 
                         Terra orientado para o norte, que estabelecem um acoplamento 
                         eletrodin{\^a}mico entre o plasma do vento solar e a 
                         magnetosfera. Em geral, esse acoplamento {\'e} controlado por 
                         estruturas dominantes emanadas do Sol como eje{\c{c}}{\~o}es de 
                         mat{\'e}ria coronal (CMEs) e suas contrapartes 
                         interplanet{\'a}rias (ICMES), em torno do m{\'a}ximo solar, e 
                         por feixes de alta velocidade corrotantes, incluindo regi{\~o}es 
                         corrotantes de intera{\c{c}}{\~a}o (CIR), nas fases descendente 
                         e de m{\'{\i}}nimo do ciclo solar. Esses feixes de alta 
                         velocidade portam ondas alfv{\^e}nicas com intensa 
                         flutua{\c{c}}{\~a}o dos par{\^a}metros f{\'{\i}}sicos do 
                         plasma, que produzem os fen{\^o}menos de atividade AE continuada 
                         de alta intensidade e de longa dura{\c{c}}{\~a}o, denominados 
                         eventos HILDCAA (high-intensity, long duration, continuous AE 
                         activity). Este estudo investiga os registros magn{\'e}ticos 
                         obtidos de observat{\'o}rios geomagn{\'e}ticos durante 
                         per{\'{\i}}odos de HILDCAA. Para esse prop{\'o}sito, tr{\^e}s 
                         condi{\c{c}}{\~o}es fundamentais do espa{\c{c}}o 
                         interplanet{\'a}rio s{\~a}o consideradas: HILDCAA (i) n{\~a}o 
                         precedida de tempestade geomagn{\'e}tica; (ii) precedida por 
                         tempestade gerada por CIR; e (iii) precedida por tempestade gerada 
                         por ICME. Um quarto caso {\'e} considerado como uma 
                         condi{\c{c}}{\~a}o de ambiente de fundo: um intervalo 
                         geomagneticamente calmo. Como metodologia de an{\'a}lises, 
                         t{\'e}cnicas wavelets para estudar caracter{\'{\i}}sticas 
                         multiescalas dos eventos HILDCAAs s{\~a}o exploradas neste 
                         trabalho. As t{\'e}cnicas de an{\'a}lises de sinais s{\~a}o 
                         compostas pela transformada wavelet cont{\'{\i}}nua, 
                         transformada wavelet discreta, correla{\c{c}}{\~a}o cruzada 
                         usando wavelet, e a usual correla{\c{c}}{\~a}o cruzada das 
                         intensidades dos sinais. De maneira complementar, uma 
                         avalia{\c{c}}{\~a}o das correntes el{\'e}tricas alinhadas com o 
                         campo geomagn{\'e}tico s{\~a}o consideradas na 
                         investiga{\c{c}}{\~a}o. Al{\'e}m disso, estimamos o potencial 
                         na regi{\~a}o polar (polar cap potential, PCP) e o campo 
                         el{\'e}trico resultante da reconex{\~a}o magn{\'e}tica (Ey), e 
                         examinamos o papel do PCP e do {\'{\i}}ndice geomagn{\'e}tico 
                         AL para monitorar a atividade geomagn{\'e}tica produzida pelos 
                         par{\^a}metros solares geoefetivos durante os eventos HILDCAAs. 
                         Assim, este trabalho contribuiu para estender a compreens{\~a}o 
                         dos eventos HILDCAAs de altas latitudes para dist{\'u}rbios 
                         ocorrendo em m{\'e}dias e baixas latitudes. H{\'a} efeitos 
                         magn{\'e}ticos relacionados a ocorr{\^e}ncias de HILDCAAs mesmo 
                         em baixas e m{\'e}dias latitudes.",
            committee = "Muralikrishna, Polinaya (presidente) and Echer, Ezequiel 
                         (orientador) and Mendes Junior, Odim (orientador) and Domingues, 
                         Margarete Oliveira (orientadora) and Dutra, Severino Luiz 
                         Guimar{\~a}es and Bolzam, Maur{\'{\i}}cio Jos{\'e} Alves and 
                         Roberto, Marisa",
           copyholder = "SID/SCD",
         englishtitle = "Efeitos relacionados a eventos HILDCAA registrados em 
                         magnet{\^o}metros de m{\'e}dia e baixa latitudes",
             language = "en",
                pages = "276",
                  ibi = "8JMKD3MGP3W34P/3J3GH78",
                  url = "http://urlib.net/rep/8JMKD3MGP3W34P/3J3GH78",
           targetfile = "publicacao.pdf",
        urlaccessdate = "29 nov. 2020"
}


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