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@PhDThesis{Yamashita:2015:VaLoPe,
               author = "Yamashita, Cristina Sayuri",
                title = "Variabilidade de longo per{\'{\i}}odo da camada F2 no setor 
                         sul-americano",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2015",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2015-08-25",
             keywords = "variabilidade solar e ionosf{\'e}rica, efeitos no clima espacial, 
                         ionossonda, digissonda, modelo climatol{\'o}gico, ionospheric and 
                         solar variability, effect on space weather, ionosonde, digisonde, 
                         climatological model.",
             abstract = "Nesta Tese de Doutorado, estudou-se a variabilidade de longo 
                         per{\'{\i}}odo do pico da ionosfera (camada F2) de baixa 
                         latitude e da regi{\~a}o equatorial do setor sul-americano 
                         baseado nos par{\^a}metros foF2, hpF2 e hmF2 obtidos atrav{\'e}s 
                         dos registros de sondagem ionosf{\'e}ricas dos s{\'{\i}}tios de 
                         Cachoeira Paulista (22,67\$^{o}\$ S, 44,99\$^{o}\$ O) e 
                         Fortaleza (3,71\$^{o}\$ S, 38,54\$^{o}\$ O), em 
                         condi{\c{c}}{\~o}es geomagneticamente calmas e {\`a}s 12 horas 
                         LT. Criaram-se modelos emp{\'{\i}}ricos baseados nos principais 
                         for{\c{c}}antes de produ{\c{c}}{\~a}o de pares de {\'{\i}}ons 
                         diurnos, isto {\'e}, na varia{\c{c}}{\~a}o de incid{\^e}ncia 
                         de radia{\c{c}}{\~a}o solar ao longo dos anos. Para tal, 
                         estudaram-se as varia{\c{c}}{\~o}es nos {\'u}ltimos 4 ciclos 
                         solares (desde 1970) dos par{\^a}metros solares: {\'{\i}}ndice 
                         do n{\'u}mero de manchas solares, fluxo de r{\'a}dio solar em 
                         10,7 cm (F10,7) e radia{\c{c}}{\~a}o no extremo ultravioleta em 
                         duas bandas (26-34 nm e 0,1-50 nm) medidas pelo instrumento 
                         SOHO/SEM. Resultados obtidos das analises hist{\'o}ricas do fluxo 
                         de radia{\c{c}}{\~a}o solar mostram que a radia{\c{c}}{\~a}o 
                         EUV emitida sofreu uma redu{\c{c}}{\~a}o de aproximadamente 
                         25\% no ciclo \#24 quando comparado ao ciclo \#23 (tendo como 
                         base o per{\'{\i}}odo de baixa atividade solar). Estes 
                         resultados indicam uma tend{\^e}ncia de diminui{\c{c}}{\~a}o na 
                         quantidade de irradi{\^a}ncia solar incidente na atmosfera 
                         terrestre, o que teria implica{\c{c}}{\~o}es para a 
                         produ{\c{c}}{\~a}o de {\'{\i}}ons por 
                         fotoioniza{\c{c}}{\~a}o. Atrav{\'e}s do estudo da variabilidade 
                         dos par{\^a}metros ionosf{\'e}ricos (excluindo a sua 
                         autovaria{\c{c}}{\~a}o devido a deposi{\c{c}}{\~a}o de energia 
                         solar atrav{\'e}s da incid{\^e}ncia de radia{\c{c}}{\~a}o), 
                         constatou-se que a quantidade de el{\'e}trons do pico da 
                         ionosfera acima de Cachoeira Paulista (baseado no par{\^a}metro 
                         foF2) diminuiu aproximadamente \$\sim\$-20\% no 
                         per{\'{\i}}odo de inverno do hemisf{\'e}rio sul e aumentou em 
                         torno de \$\sim\$15\% no per{\'{\i}}odo de ver{\~a}o, 
                         apesar da tend{\^e}ncia negativa de decr{\'e}scimo da respectiva 
                         altitude do pico (par{\^a}metros hpF2 e hmF2). Tal comportamento 
                         aponta para a poss{\'{\i}}vel varia{\c{c}}{\~a}o da escala de 
                         altura do oxig{\^e}nio at{\^o}mico ao longo dos anos, e que esta 
                         variabilidade {\'e} fortemente modulada pelo per{\'{\i}}odo do 
                         ano. Para Fortaleza, notou-se que o par{\^a}metro foF2 teve uma 
                         tend{\^e}ncia positiva entre 13-24\% para quase todo o ano. Os 
                         par{\^a}metros hpf2, hmf2 mostraram tend{\^e}ncia negativa de 
                         \$\sim\$-11-14\% em julho, positiva de \$\sim\$+10-18\% no 
                         ver{\~a}o e equin{\'o}cios. ABSTRACT: In this thesis, the long 
                         term variability of the peak of the ionosphere (F2 layer) at 
                         low-latitude and equatorial regions of the South American sector 
                         is studied. This work is based on foF2, hpF2 and hmF2 parameters 
                         obtained through the ionospheric sounding records of the sites 
                         from Cachoeira Paulista (22,67\$^{o}\$ S, 44,99\$^{o}\$ O) and 
                         Fortaleza (3,71\$^{o}\$ S, 38,54\$^{o}\$ O). Data during quiet 
                         geomagnetic conditions at 12 LT (Local Time) were studied. 
                         Empirical models were created based on the main forcing production 
                         of diurnal ion pairs, that is, variation in the incidence of solar 
                         radiation over the years. In order to perform this study, the 
                         variations in solar parameters over the past four solar cycles 
                         (since 1970) have been studied: the index number of sunspots, 
                         solar radio flux at 10.7 cm (F10.7) and extreme ultraviolet 
                         radiation in two bands (26-34 nm and 0.1-50 nm) measured by 
                         SOHO/SEM instrument. Results of the historical analysis of the 
                         solar radiation flux show that the EUV radiation was reduced by 
                         approximately 25\% in the cycle \# 24 compared to the cycle \# 
                         23. These results indicate a decreasing trend in the quantity of 
                         incident solar irradiance at the Earth\${}\$s atmosphere, which 
                         would have implications for the production of ions by 
                         photoionization. Through the study of variation of ionospheric 
                         parameters (excluding the auto variation due to deposition of 
                         solar energy by radiation incidence) it was found that the amount 
                         of peak electrons of the ionosphere above Cachoeira Paulista 
                         (based on foF2 parameter) decreased approximately 
                         \$\sim\$-20\% during the southern hemisphere winter and 
                         increased by around \$\sim\$ -15\% during the summer. Such 
                         behavior indicates the range of possible variation in height of 
                         the atomic oxygen over the years, and this variability is strongly 
                         modulated by the period of the year. For Fortaleza, it was noted 
                         that the parameter foF2 showed a positive trend between 13-24\% 
                         for most of the year. The parameters hpf2, hmF2 showed a negative 
                         trend of \$\sim\$ -11-14\% in July, and a positive trend of 
                         \$\sim\$ +10-18\% in summer and equinoxes.",
            committee = "Dal Lago, Alisson (presidente) and Echer, Ezequiel (orientador) 
                         and Echer, Mariza Pereira de Souza (orientadora) and Alarcon, 
                         Alicia Luisa Cl{\'u}a de Gonzalez and Sobral, Jos{\'e} Humberto 
                         Andrade and Pacini, Alessandra Abe and Bertoni, Fernando Celso 
                         Perin",
           copyholder = "SID/SCD",
         englishtitle = "Long term variability of F2 layer in the South American sector",
             language = "pt",
                pages = "119",
                  ibi = "8JMKD3MGP3W34P/3K5FA2L",
                  url = "http://urlib.net/rep/8JMKD3MGP3W34P/3K5FA2L",
           targetfile = "publicacao.pdf",
        urlaccessdate = "01 dez. 2020"
}


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