@PhDThesis{Barbosa:2012:PaAlVo,
author = "Barbosa, Tatiane Felinto",
title = "Padr{\~o}es de alta vorticidade potencial sobre o Oceano
Atl{\^a}ntico Sul tropical e caracter{\'{\i}}sticas
atmosf{\'e}ricas associadas",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2012",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2011-12-16",
keywords = "vorticidade potencial, quebra da onda de Rosby, Oceano
Atl{\^a}ntico Sul, padr{\~o}es atmosf{\'e}ricos,
intrus{\~o}es, potential vorticity, Rossby wave breaking, South
Atlantic Ocean, atmospheric patters, intrusion.",
abstract = "Neste estudo foram analisados os padr{\~o}es de alta vorticidade
potencial (AVP) no n{\'{\i}}vel isentr{\'o}pico de 350 K sobre
o Oceano Atl{\^a}ntico Sul (OAS) no per{\'{\i}}odo de
ver{\~a}o entre 1979-2001. As rean{\'a}lises ERA-40 foram
utilizadas na an{\'a}lise observacional enquanto que tr{\^e}s
simula{\c{c}}{\~o}es com o Modelo de Circula{\c{c}}{\~a}o
Geral (MCGA) do CPTEC foram utilizadas para an{\'a}lise das
caracter{\'{\i}}sticas representadas pelo modelo. Na
identifica{\c{c}}{\~a}o dos padr{\~o}es de AVP considerou-se a
incurs{\~a}o da VP em 350 K de -1,5 UVP atingindo a latitude de
\$10°\$S. O m{\'e}todo de Fun{\c{c}}{\~o}es Ortogonais
Emp{\'{\i}}ricas foi aplicado no campo de VP nestes dias para
determinar os padr{\~o}es de AVP sobre o OAS tropical, e as
caracter{\'{\i}}sticas atmosf{\'e}ricas associadas a tais
padr{\~o}es foram determinadas por meio da t{\'e}cnica de
compostos. Os tr{\^e}s primeiros modos apresentaram a maior parte
da vari{\^a}ncia explicada e distintos padr{\~o}es de AVP. Os
padr{\~o}es identificados na an{\'a}lise observacional e
num{\'e}rica foram similares, com diferen{\c{c}}a na
posi{\c{c}}{\~a}o dos mesmos, sendo que no modelo a AVP
encontra-se deslocada para oeste em rela{\c{c}}{\~a}o ao
observado. Este comportamento teve influ{\^e}ncia sobre a
precipita{\c{c}}{\~a}o do modelo. O primeiro modo (CP1)
apresentou um padr{\~a}o de intrus{\~a}o de AVP com
orienta{\c{c}}{\~a}o norte-sul sobre o OAS tropical pr{\'o}ximo
ao Nordeste do Brasil (NEB), influenciando a
precipita{\c{c}}{\~a}o desta regi{\~a}o. {\`A} medida que a
intrus{\~a}o desloca-se para leste, a precipita{\c{c}}{\~a}o no
sul do NEB intensifica-se. A componente 2 (CP2) apresentou uma
incurs{\~a}o de AVP com quebra de onda de Rossby (QOR)
anticicl{\^o}nica associada. Neste caso, o comportamento de
precipita{\c{c}}{\~a}o sobre o NEB foi semelhante {\`a} CP1. No
terceiro modo (CP3), h{\'a} configura{\c{c}}{\~a}o de QOR
anticicl{\^o}nica com forma{\c{c}}{\~a}o de um v{\'o}rtice
cicl{\^o}nico (VC) sobre o leste do NEB. Este padr{\~a}o inibe a
precipita{\c{c}}{\~a}o no leste e sul do NEB, mas ocorre
convec{\c{c}}{\~a}o nas regi{\~o}es circunvizinhas. Nas
tr{\^e}s componentes, o \textquotedblleft{duto de
oeste}\textquotedblright encontrava-se intenso na
forma{\c{c}}{\~a}o e desenvolvimento e desintensificou-se nos
dias seguintes enquanto que a corrente de jato (CJ) apresentou
comportamento contr{\'a}rio. Foi visto que a presen{\c{c}}a
destas intrus{\~o}es de AVP sobre o OAS tropical impede a
propaga{\c{c}}{\~a}o meridional das ondas barocl{\'{\i}}nicas.
A variabilidade interanual dos eventos identificados na CP1 e CP2
foi associada ao fen{\^o}meno ENOS. O n{\'u}mero de eventos
identificados no MCGA correspondeu {\`a} metade do visto na
observa{\c{c}}{\~a}o. A import{\^a}ncia dos ventos em altos
n{\'{\i}}veis na regi{\~a}o equatorial e nas latitudes
m{\'e}dias do OAS s{\~a}o ressaltadas nessa
compara{\c{c}}{\~a}o, pois o vento zonal da regi{\~a}o
equatorial foi climatologicamente mais fraco e a CJ mais intensa
nos resultados do modelo. Na variabilidade interanual da CP1, os
anos com {\'{\I}}ndice de Oscila{\c{c}}{\~a}o Sul negativo
(IOSN) e positivo (IOSP) apresentaram muitos e poucos casos de
intrus{\~a}o, respectivamente. Contudo, h{\'a} uma
varia{\c{c}}{\~a}o entre-ENOS. Os anos nos quais foram
observadas intrus{\~o}es, tanto em anos de El niņo (EN), La niņa
(LN) e neutro (N), apresentaram \textquotedblleft{duto de
oeste}\textquotedblright intensos, Alta da Bol{\'{\i}}via
fraca, Cavado no Nordeste intenso, fraco vento zonal de oeste
sobre o norte da Argentina e maior amplitude da onda 3.
Caracter{\'{\i}}sticas opostas foram vistas nos anos de EN, LN e
N quando ocorreram poucos casos de intrus{\~o}es. Este trabalho
mostrou que alguns padr{\~o}es de AVP sobre o OAS tropical podem
influenciar a quebra de onda. Tamb{\'e}m foi visto que a
convec{\c{c}}{\~a}o associada aos sistemas frontais em
superf{\'{\i}}cie apresenta um importante papel na quebra da
onda, que por sua vez afeta a precipita{\c{c}}{\~a}o sobre o
NEB. A posi{\c{c}}{\~a}o da anomalia cicl{\^o}nica de AVP inibe
ou favorece a convec{\c{c}}{\~a}o sobre esta regi{\~a}o.
ABSTRACT: Analysis of high potential vorticity (high-PV) patterns
in the 350 K isentropic level over the South Atlantic Ocean (SAO)
was performed in the summer season during 1979- 2001. The ERA-40
reanalysis was used for the observational analysis and three
simulations with the CPTEC Atmospheric General Circulation Model
(AGCM) were analyzed to verify the model ability in representing
the observed features. The high- PVcases were obtained from
incursions of PV of -1.5 UVP at 350 K reaching the \$10°\$S
latitude. The Empirical Orthogonal Function (EOF) method was
applied in the field of potential vorticity (PV) of the selected
days to determine patterns of high-PV on the tropical OAS. The
atmospheric features associated with the dominant patterns were
analyzed through composites. The first three modes explained the
largest part of the variance and distinct patterns of high-PV,
with similar characteristics in the observational and model
analysis. However there was an eastward shifting of the model
patterns compared to the observations. This behavior had an
influence on the model precipitation. The first mode (CP1) showed
a pattern of high-PV intrusion with north- south orientation over
the OAS, near the tropical northeastern Brazil (NEB), intensifying
the precipitation as the intrusion moves to the east. The second
mode (PC2) showed incursion of high-PV with an anticyclonic Rossby
wave breaking (RWB) and the same influence in the precipitation
over the NEB as showed in CP1. In the third mode (CP3), there is
formation of a cyclonic vortex (CV) over the eastern NEB,
inhibiting the precipitation in the east and south of this region,
with convection in the surrounding regions. In the three modes,
the \textquotedblleft{westerly ducts}\textquotedblright were
intense during the high-PV formation, and the development became
less intense on the following days. The jet stream (JS) showed
opposite behavior. It was found that the presence of these high-PV
intrusions on the SAO prevents the meridional propagation of
baroclinic waves. The interannual variability of the events
identified in CP1 and CP2 were associated with ENSO. The events
identified in the AGCM correspond to half of the observed. The
importance of high level winds in the equatorial and middle
latitudes of the SAO are emphasized in this comparison, because
the equatorial zonal wind was climatologically weaker and JS
stronger in the model results. In the interannual variability of
CP1, the years with negative Southern Oscillation Index (SOIN) and
positive (SOIP) had many and few cases of intrusion, respectively.
However, there is variation inter-ENSO. The years with intrusions
observed in El Niņo (EN), La Niņa (LN) and neutral (N) conditions,
presented intense \textquotedblleft{westerly
ducts}\textquotedblright, weakening of the Bolivian high, intense
northeast trough, weak zonal west winds over northern Argentina
and great amplitude of wavenumber 3. Opposite characteristics were
observed in the EN, LN and N years when there were few cases of
intrusions. Some patterns of high-PV on the SAO can have an
influence on tropical wave breakings. The convection associated
with frontal systems presents an important role on the wave
breaking, which affects the precipitation over the NEB. The
position of the high-PV cyclonic anomaly inhibits or favors
convection over this region.",
committee = "Sansigolo, Cl{\'o}vis Angeli (presidente) and Gan, Manoel Alonso
(vice-presidente) and Cavalcanti, Iracema Fonseca de Albuquerque
(orientador) and Silva, Maria Gertrudes Alvarez Justi da and
M{\"u}ller, Gabriela Viviana",
copyholder = "SID/SCD",
englishtitle = "High potential vorticity patterns over tropical South Atlantic and
associated atmospheric features",
language = "pt",
pages = "239",
ibi = "8JMKD3MGP7W/3ASNMFB",
url = "http://urlib.net/ibi/8JMKD3MGP7W/3ASNMFB",
targetfile = "publicacao.pdf",
urlaccessdate = "17 maio 2024"
}