@MastersThesis{Souza:1992:EsCiSu,
author = "Souza, Ronald Buss de",
title = "Estudo da circula{\c{c}}{\~a}o superficial ao norte do Estreito
de Bransfield, Ant{\'a}rtica",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "1992",
address = "Sao Jose dos Campos",
month = "1992-09-08",
keywords = "oceanografia, estreito de Bransfield, Ant{\'a}rtica
(Regi{\~a}o), b{\'o}ias de deriva, NOAA-10, NOAA-11,
meteorol{\'o}gia, sat{\'e}lites NOAA, fen{\^o}meno mesoescala,
correntes oce{\^a}nicas, superf{\'{\i}}cie do mar, analise de
trajet{\'o}ria, analise espectral, paramentos
oceanogr{\'a}ficos, oscila{\c{c}}{\~a}o, ocean{\'o}grafo,
autocorrelation, buoys, maximum entropy method, mesoscale
phenomena, ocean current, ocean surface, spectrun analysis,
trajectory analysis, NOAA satellites, oscilation.",
abstract = "Um estudo sobre a circula{\c{c}}{\~a}o superficial em
meso-escala na regi{\~a}o ao Norte do Estreito de Bransfield,
Ant{\'a}rtica (61-62°S, 52.5-58.5°W) e apresentado, utilizando-se
medidas de corrente efetuadas por uma boia de deriva brasileira
rastreada pelos sat{\'e}lites NOAA 10 e 11 no per{\'{\i}}odo de
26/01-21/02/89. Dados de posicionamento da boia, juntamente com
dados oceanogr{\'a}ficos e meteorol{\'o}gicos auxiliares tomados
{"}in situ{"} serviram para uma descri{\c{c}}{\~a}o detalhada da
corrente superficial na {\'a}rea de estudo. Com uma velocidade
m{\'e}dia de 7.5 cm/s e dire{\c{c}}{\~a}o altamente zonal
(89º), a corrente medida pela boia foi, em grande parte, regida
pelos ventos da regi{\~a}o, conforme o modelo de Ekman. As
correntes de Ekman foram calculadas para 0 e 10 metros, obtendo-se
21 e 8.5 cm/s nas dire{\c{c}}{\~o}es 108° e 25°,
respectivamente. O padr{\~a}o de circula{\c{c}}{\~a}o medido
pela boia n{\~a}o concordou com a circula{\c{c}}{\~a}o
geostr{\'o}fica regional. As correntes geostr{\'o}ficas
m{\'e}dias em 0 e 10 metros foram cerca de 2 cm/s na
dire{\c{c}}{\~a}o para Norte. An{\'a}lises das energias
cin{\'e}ticas Total (ECT), Media (ECM) e de V{\'o}rtices (ECV)
demonstraram que as flutua{\c{c}}{\~o}es de meso-escala medidas
pela ECV compreenderam 91.7% da ECT. Em valores absolutos, a ECM e
a ECV foram iguais a 28.1 cm2/s2 e 357.4 cm2/s2, respectivamente.
Atrav{\'e}s da auto-correla{\c{c}}{\~a}o, determinou-se que as
s{\'e}ries de deslocamento da boia cont{\'e}m per{\'{\i}}odos
dominantes de 21.7 na s{\'e}rie zonal, e de 11.5 dias na
s{\'e}rie meridional. Usando a an{\'a}lise espectral pelo
M{\'e}todo da M{\'a}xima Entropia (MEM), determinou-se que 75.9%
da energia total da componente zonal foi relacionada a
per{\'{\i}}odos de 14.9 a 37.7 dias. Para a componente
meridional do deslocamento da boia, 66.2% da energia relacionou-se
a per{\'{\i}}odos entre 11.5 e 21.2 dias. A MEM tamb{\'e}m
demonstrou que per{\'{\i}}odos de 4-5 dias e 1 dia (causado por
mar{\'e}s) foram importantes nas duas s{\'e}ries componentes.
Compara{\c{c}}{\~o}es entre os per{\'{\i}}odos obtidos pela
MEM para os dados da boia, e os obtidos para dados de press{\~a}o
atmosf{\'e}rica recolhidos na Esta{\c{c}}{\~a}o Ant{\'a}rtica
Brasileira, mostraram que a for{\c{c}}ante atmosf{\'e}rica foi
respons{\'a}vel por oscila{\c{c}}{\~o}es sentidas na corrente
em per{\'{\i}}odos de 25.5, 11-12 e 5-6 dias. An{\'a}lises de
correla{\c{c}}{\~a}o cruzada dos dados da boia e de dados de
press{\~a}o atmosf{\'e}rica mostraram que a corrente responde ao
for{\c{c}}amento atmosf{\'e}rico com um retardo de tempo de 14
dias. Este per{\'{\i}}odo parece estar relacionado a
varia{\c{c}}{\~o}es em grande escala do sistema
atmosf{\'e}rico. An{\'e}is ou {"}loops{"} presentes na
trajet{\'o}ria da boia foram produzidos por mar{\'e}s diurnas,
as componentes de mar{\'e} mais importantes na {\'a}rea de
estudo. O aparecimento destes {"}loops{"} na trajet{\'o}ria da
boia esteve relacionado {\`a} presen{\c{c}}a de uma frente
oce{\^a}nica localizada a Oeste da {\'a}rea de estudo. Uma
segunda frente, a Leste, com encontro de {\'a}guas de
influ{\^e}ncia do Mar de Bellingshausen com {\'a}guas mais frias
e salinas do Mar de Weddell resultou em uma corrente que causou
uma forte deflec{\c{c}}{\~a}o da boia para a dire{\c{c}}{\~a}o
Sul. A utiliza{\c{c}}{\~a}o da boia de deriva brasileira
compat{\'{\i}}vel com o sistema ARGOS comprovou ser uma
ferramenta eficiente para estudos em meso-escala, com a
possibilidade de evid{\^e}ncia de frentes oce{\^a}nicas, fluxos
de massas de {\'a}gua de caracter{\'{\i}}sticas conhecidas, e
influ{\^e}ncias da atmosfera e mar{\'e}s nas correntes
superficiais. Resultados de estudos como o realizado aqui servem
de base para trabalhos mais complexos na {\'a}rea de
intera{\c{c}}{\~a}o ar-mar, climatologia e
distribui{\c{c}}{\~a}o de organismos plact{\^o}nicos de
interesse comercial, por exemplo. ABSTRACT: A study of the
meso-seale circulation to the North of Bransfield Strait,
Antarctica (61-62°S, 52.5-58.5°W), utilizing the displacement
trajectory of a Brazilian drifting buoy, tracked by NOAA 10 and 11
satellites during 01/26-02/21/89, is presented. Buoy positional
data, together with in situ oceanographic and meteorological data,
were used to obtain a detailed description of the surface current.
With a mean velocity of 7.5 cm/s, and a highly zonal direction
(89°), the current derived from the buoy trajectory was, in great
part, forced by the winds, in agreement with the Ekman model. The
Ekman currents were computed for O and 10 meter depths, obtaining
21 and 8.5 cm/s toward 108° and 25°, respectively. The regional
geostrophic circulation for the surface and 10 meter levels
disagreed with the circulation pattern measured by the buoy. The
mean geostrophic currents at those levels were about 2 cm/s to the
North. Analysing the Total, Mean and the Eddy Kinetic Energies
(EKT, EKM and EKE, respectively), it was found that time-variable
flutuations measured by EKE comprised 91.7% of the EKT. In
absolute values, EKM and EKE were equal to 28.1 cm2 /s2 and 357.4
cm2 /s2, respectively. With the use of auto-correlational
analysis, it was determined that the displacement series of the
buoy' s trajectory contain dominant zonal and meridional component
periods of 21.7 and 11.5 days, respectively. Using the Maximum
Entropy Method (MEM) of spectral analysis, it was determined that
75.9% of total zonal energy was related to periods of 14.9 to 37.7
days. For the meridional component of the residual displacement
series, 66.2% of the energy was related to periods between 11.5
and 21.2 days. The MEM analysis also shows that periods of 4-5
days and 1 day (tidal) were important in both displacement series.
Comparison of the periods obtained from MEM for buoy and
atmospheric pressure time series measured at the Brazilian
Antarctic Station, showed that the atmospheric forcing was
responsable for the 25.5, 11-12 and 5-6 days oscillations in the
current. Cross-correlational analysis of buoy dispacement and
atmospheric pressure series shows that the currents follow the
atmospheric forcing with a lag of 14 days. This period seems to be
related to large-scale variation in the atmospheric system.
Displacement loops present in the buoy' s trajectory are shown to
be caused by diurnal tides, the most important tidal component in
the study region. The appearance of these loops in the buoy's
trajectory was related to the presence of an oceanic front,
localized in the western part of the study area. A second front to
the East, formed by the justaposition of water influenced by the
Bellingshausen Sea and the more cold and saline water from the
Weddell Sea, resulted in a current that caused a strong southward
deflection of the buoy. The utilization of the ARGOS compatible
Brazilian drifting buoy is shown to be an efficient tool in
meso-scale studies, offering the possibility of delineating
oceanic fronts, fluxes of water masses with known characteristics,
and atmospheric and tidal influences on the surface currents.
Results of studies like this one can be used as support to more
complexes studies in the areas of air-sea interaction,
climatology, and distribution of planctonic organisms of economic
interest, for example.",
committee = "Stevenson, Merrit Raymond (presidente/orientador) and Lorenzzetti,
Jo{\~a}o Antonio and Ferreira, Nelson Jesus and Miranda, Luiz
Bruner de",
copyholder = "SID/SCD",
englishtitle = "Study of the surface circulation to the North of Bransfield
Strait, Antarctica",
label = "6619",
language = "pt",
pages = "189",
ibi = "6qtX3pFwXQZ3r59YD6/GP3oJ",
url = "http://urlib.net/rep/6qtX3pFwXQZ3r59YD6/GP3oJ",
targetfile = "publicacao.pdf",
urlaccessdate = "24 maio 2020"
}