Fechar
Metadados

@PhDThesis{Gomes:2019:EsCaVe,
               author = "Gomes, Tiago Francisco Pinheiro",
                title = "Eventos extremos e estruturas coerentes na turbul{\^e}ncia: 
                         estudo de caso para o vento solar",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2019",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2018-10-19",
             keywords = "vento solar, estruturas coerentes, eventos extremos, 
                         turbul{\^e}ncia, v{\'o}rtices magn{\'e}ticos, solar wind, 
                         coherent structures, extreme events, turbulence, magnetic 
                         vortices.",
             abstract = "Na presente tese, s{\~a}o aplicadas t{\'e}cnicas 
                         estat{\'{\i}}sticas para modelagens de distribui{\c{c}}{\~o}es 
                         de eventos extremos, detec{\c{c}}{\~a}o de l{\^a}minas de 
                         correntes, an{\'a}lises de turbul{\^e}ncia intermitente e 
                         detec{\c{c}}{\~a}o de Dragon Kings em dados observacionais e 
                         simulados do vento solar. Mostramos que l{\^a}minas de correntes 
                         s{\~a}o as estruturas coerentes respons{\'a}veis pela 
                         presen{\c{c}}a de turbul{\^e}ncia bem desenvolvida de Kolmogorov 
                         em s{\'e}ries temporais do m{\'o}dulo do campo magn{\'e}tico do 
                         vento solar, al{\'e}m de serem as grandes respons{\'a}veis pela 
                         positividade do par{\^a}metro de forma, principal par{\^a}metro 
                         da teoria cl{\'a}ssica de valores extremos e respons{\'a}vel por 
                         caracterizar o comportamento das caudas das 
                         distribui{\c{c}}{\~o}es generalizadas de Pareto e de valores 
                         extremos. Propomos uma nova t{\'e}cnica para detec{\c{c}}{\~a}o 
                         de l{\^a}minas de correntes e reconex{\~o}es magn{\'e}ticas 
                         baseada na volatilidade. Al{\'e}m disto, propomos uma prova 
                         te{\'o}rica para a objetividade de uma nova t{\'e}cnica 
                         lagrangiana de detec{\c{c}}{\~a}o de v{\'o}rtices 
                         magn{\'e}ticos, validando sua utiliza{\c{c}}{\~a}o em plasmas 
                         espaciais. Baseado no campo de velocidades, propomos uma nova 
                         t{\'e}cnica euleriana e independente do referencial para 
                         detec{\c{c}}{\~a}o de centros vorticais. Identificamos 
                         inconsist{\^e}ncias em t{\'e}cnica lagrangiana e objetiva de 
                         detec{\c{c}}{\~a}o de v{\'o}rtices baseados na vorticidade 
                         quando aplicado em plasma solar, para o qual propomos uma 
                         solu{\c{c}}{\~a}o. Para a modelagem estat{\'{\i}}stica de 
                         eventos extremos, utilizamos a teoria cl{\'a}ssica de eventos 
                         extremos, a qual se baseia nas t{\'e}cnicas de picos acima de um 
                         limiar e de m{\'a}ximos em blocos. Para a simula{\c{c}}{\~a}o 
                         de ambiente interplanet{\'a}rio, utilizamos simula{\c{c}}{\~a}o 
                         MHD-3D compress{\'{\i}}vel, adiab{\'a}tica e com 
                         for{\c{c}}ante n{\~a}o helicoidal. Fomos os primeiros a aplicar 
                         com sucesso a teoria de Dragon Kings em dados do vento solar, 
                         encontrando fortes evid{\^e}ncias de que reconex{\~o}es 
                         magn{\'e}ticas pertencem a esta classe especial de eventos 
                         extremos. Para as an{\'a}lises estat{\'{\i}}sticas de Dragon 
                         Kings, utilizamos o teste-U, teste-DK e intervalos de 
                         confian{\c{c}}a para distribui{\c{c}}{\~o}es de leis de 
                         pot{\^e}ncia. ABSTRACT: In the present work, statistical 
                         techniques are employed in the modelling of extreme events 
                         distributions, detection of current sheets, analysis of 
                         intermittent turbulence and detection of Dragon Kings in 
                         observational and simulated solar wind data. We have shown that 
                         current sheets are the principal coherent structures responsible 
                         for the presence of Kolmogorov turbulence in solar wind time 
                         series of the modulus of magnetic field, as well as being 
                         responsible for the positivity of the shape parameter, the main 
                         parameter of extreme values theory and responsible for 
                         characterizing the tails behavior of generalized Pareto and 
                         extreme values distributions. We propose a new technique for 
                         detection of current sheets and magnetic reconnections based on 
                         volatility. Additionally, we propose a mathematical proof for the 
                         objectivity of a new technique for the detection of magnetic 
                         vortices, validating its application in space plasmas. Based on 
                         the velocity field, we propose a new frame invariant eulerian 
                         technique for vortex centers detection. We identified 
                         inconsistencies in lagrangian and objective vortex detection 
                         technique based on vorticity when applied to solar plasma, for 
                         which we propose a solution. For the statistical modelling of 
                         extreme events, the classical theory of extreme events is adopted, 
                         which is based on the peaks over threshold and block maxima 
                         techniques. For the interplanetary environment simulation, 3D 
                         compressible and adiabatic MHD simulations are used with a 
                         nonhelical forcing. We were the first to successfully apply the 
                         dragon kings theory to solar wind data, finding strong evidence 
                         that magnetic reconnections belong to this special class of 
                         extreme events. For the statistical analyses of Dragon Kings, the 
                         U-test and the DK-test are adopted.",
            committee = "Alves, Maria Virg{\'{\i}}nia (presidente) and Rempel, Erico Luiz 
                         (orientador) and Long-Chian, Abraham Chian (orientador) and Ramos, 
                         Fernando Manuel (orientador) and Dallaqua, Renato Sergio and 
                         Cerda, Rodrigo Andr{\'e}s Miranda and Roberto, Marisa",
         englishtitle = "Extreme events and coherent structures in turbulence: a case study 
                         for the solar wind",
             language = "pt",
                pages = "271",
                  ibi = "8JMKD3MGP3W34R/3S94U7P",
                  url = "http://urlib.net/rep/8JMKD3MGP3W34R/3S94U7P",
           targetfile = "publicacao.pdf",
        urlaccessdate = "03 dez. 2020"
}


Fechar