@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/ibi/8JMKD3MGP3W34P/3J3GH78",
targetfile = "publicacao.pdf",
urlaccessdate = "26 abr. 2024"
}