@MastersThesis{Adebayo:2021:StUsGr,
author = "Adebayo, Oluwasegun Micheal",
title = "Plasma blobs in the tropical region: a study using ground-based
optical and radio techniques and multisatellite data",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2021",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2021-07-12",
keywords = "aeronomy, plasma bubbles and blobs, lifetime, aeroluminiscence,
all-sky imagers, aeronomia, blobs e bolhas de plasma, tempo de
vida, aeroluminesc{\^e}ncia, imageadores all-sky.",
abstract = "Plasma bubbles and plasma blobs are nighttime phenomena in the
ionosphere. Bubbles and blobs have been characterized as the
regions of plasma depletions and enhancements, respectively. The
relationship between the two phenomena has been a subject of
research recently and some authors claimed them to be causally
related but some claimed them to be independent. In this work, we
have studied the occurrence characteristics of plasma
enhancements, blobs, and plasma depletions, bubbles, during high
solar activity (HSA), and low solar activity (LSA) for the period
of two years. OI 630.0 nm emission images from two all-sky imagers
at the tropical region over the Brazilian sector were used to
study the occurrence characteristics of plasma blobs and bubbles.
The intensity enhancements in the airglow images are the optical
signature at the height range of the emitting layer of plasma
blobs. An all-sky imaging system, observing the OI 630.0 nm
emission, was operational at Cachoeira Paulista (22.7oS, 45.0oW;
16oS dip latitude), Brazil, during the period from October 1998 to
July 2000. Also, an all-sky imager, observing OI 630.0 nm
emission, has been operational at the Cuieiras Biological Reserve
(also commonly referred to as ZF-2: 2.58oS, 60.22oW), Brazil,
since August 2015 till date. About 3,000 images collected from
both imagers were analyzed in this work and the results are
presented. The occurrence patterns of both the plasma bubbles and
blobs are seasonal dependent, and with the highest occurrence
frequency during summer for both HSA and LSA. During HSA, 95% of
plasma blobs observed were associated with plasma bubbles while
every single plasma blobs observed during LSA were associated with
plasma bubbles; 100%. Notice that not all the plasma bubbles
observed were associated with plasma blobs. The Pearson
correlation coefficients, based on the monthly hours of the
occurrence of plasma blobs and plasma bubbles, during both HSA and
LSA, were +0.738 and +0.870, respectively. The average visibility
time of plasma blobs, based on their time of appearance and
disappearance from the field of view of the all-sky imagers,
during HSA and LSA, was 1.08 hr and 0.57 hr, respectively. On the
other hand, the average visibility time of plasma bubbles, during
HSA and LSA, was 4.01 hr and 2.19 hr, respectively. Also, during
HSA and LSA, the plasma blob had an east-west spatial extension of
54-83 km and 41- 81 km, respectively. The north-south spatial
extension, during HSA and LSA, was 87-129 km and 110-230 km. The
nocturnal variation of plasma blobs during HSA and LSA displays
different characteristics. Plasma blobs are likely to be formed
just after the post-sunset but get fully developed during midnight
and vanish just after midnight mostly. We observed, for the first
time, plasma blob merging and detachment. Hence, in this work, we
have found a strong relationship between the plasma depletions
(bubbles) and plasma enhancements (blobs) in the nighttime
ionosphere. In addition, plasma enhancements associated with large
plasma depletions observed by SWARM constellation satellites are
also discussed in this work. RESUMO: Bolhas de plasma e aumentos
localizados na densidade de plasma (blobs) s{\~a}o fen{\^o}menos
noturnos na ionosfera. Bolhas e {"}blobs{"}s{\~a}o caracterizados
como regi{\~o}es de deple{\c{c}}{\~o}es e
intensifica{\c{c}}{\~o}es do plasma, respectivamente. A
rela{\c{c}}{\~a}o entre os dois fen{\^o}menos tem sido objeto
de pesquisa recentemente e alguns autores afirmam que s{\~a}o
fen{\^o}menos complementares, mas alguns afirmam que s{\~a}o
independentes. Neste trabalho, determinamos a frequ{\^e}ncia de
ocorr{\^e}ncia dos {"}blobs{"}assim como a das bolhas de plasma,
durante atividade solar alta (HSA) e baixa (LSA) pelo
per{\'{\i}}odo de dois anos. Imagens obtidas atrav{\'e}s da
emiss{\~a}o OI 630,0 nm na regi{\~a}o tropical brasileira foram
usadas para estudar as caracter{\'{\i}}sticas de ocorr{\^e}ncia
de {"}blobs{"}. Um dos imageadores operou na cidade de Cachoeira
Paulista (22.7oS, 45.0oW; 16oS dip latitude) Brasil, durante o
per{\'{\i}}odo de outubro de 1998 a julho de 2000 (atividade
solar alta). Um outro imageador operando na regi{\~a}o
Amaz{\^o}nica (2.58oS, 60.22oW). Cerca de 3000 imagens de OI
630,0 nm foram analisadas para LSA e HSA. O estudo mostrou que a
frequ{\^e}ncia de ocorr{\^e}ncia das bolha e dos
{"}blobs{"}{\'e} sazonal tendo uma maior frequ{\^e}ncia de
ocorr{\^e}ncia durante o ver{\~a}o para per{\'{\i}}odos de HSA
e LSA. Durante a HSA, approximadamente 95% das
{"}blobs{"}est{\~a}o associados a ocorr{\^e}ncia das bolhas de
plasma. Por outro lado, h{\'a} casos em que h{\'a} bolhas
por{\'e}m n{\~a}o h{\'a} {"}blobs{"}ou vice-versa. A
correla{\c{c}}{\~a}o de Pearson, baseada nas horas mensais de
ocorr{\^e}ncia de plasma e {"}blobs{"}, durante HSA e LSA, foram
de +0, 738 e +0, 870, respectivamente. O tempo m{\'e}dio de vida
dos {"}blobs{"}, com base em seu tempo de aparecimento e
desaparecimento no campo de vis{\~a}o do imageador, durante
per{\'{\i}}odos de HSA e LSA, foi de 1,08 horas e 0,57 horas,
respectivamente. J{\'a} o tempo m{\'e}dio de vida das bolhas de
plasma, durante per{\'{\i}}odo de HSA e LSA, foi de 4,01 horas e
2,19 horas, respectivamente. Os {"}blobs{"}come{\c{c}}am a se
formar logo ap{\^o}s o p{\^o}r do sol, alcan{\c{c}}ando o
m{\'a}ximo desenvolvimento por volta da a meia-noite. Observamos
pela primeira vez a fus{\~a}o e o desprendimento de um
{"}blob{"}. Tamb{\'e}m encontramos uma forte rela{\c{c}}{\~a}o
entre o aparecimento de deple{\c{c}}{\~o}es de plasma (bolhas) e
aumentos de plasma (blobs) na ionosfera noturna. Al{\'e}m disso,
{"}blobs{"}e bolhas de plasma foram observados pela
constela{\c{c}}{\~a}o de sat{\'e}lites SWARM e o resultado
{\'e} apresentado.",
committee = "Dal lago, Alisson (presidente) and Pimenta, Alexandre Alvares
(orientador) and Bittencourt, Jos{\'e} Augusto and Meneses
Junior, Francisco Carlos de",
englishtitle = "Blobs de plasma na regi{\~a}o tropical: um estudo usando
t{\'e}cnicas {\'o}pticas e de r{\'a}dio baseadas em terra e
dados multisat{\'e}lite",
language = "en",
pages = "118",
ibi = "8JMKD3MGP3W34T/4552AL2",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/4552AL2",
targetfile = "publicacao.pdf",
urlaccessdate = "21 maio 2024"
}