@PhDThesis{Andrade:2018:PaTeDe,
author = "Andrade, Kelen Martins",
title = "O papel das teleconex{\~o}es e de fatores regionais que
influenciam a ocorr{\^e}ncia de precipita{\c{c}}{\~a}o extrema
associada a sistemas frontais sobre o Sudeste do Brasil",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2018",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2017-12-05",
keywords = "frentes frias, precipita{\c{c}}{\~a}o, teleconex{\~o}es, cold
fronts, precipitation, teleconnections.",
abstract = "Neste estudo foram analisados casos de sistemas frontais que
provocam chuva extrema (percentil de 5\% e 95\%) em uma
{\'a}rea do Sudeste do Brasil e a influ{\^e}ncia exercida por
teleconex{\~o}es e padr{\~o}es de grande escala e regional. Essa
{\'a}rea foi escolhida por estar sujeita a deslizamentos e
enchentes no ver{\~a}o e primavera. Os casos de frentes que
provocam chuvas intensas podem contribuir para esses desastres, e
portanto, o entendimento das diferen{\c{c}}as entre os eventos
chuvosos e secos associados aos sistemas frontais t{\^e}m
significativa import{\^a}ncia. As an{\'a}lises foram feitas
usando dados de rean{\'a}lise (CFSR) e do Modelo de
Circula{\c{c}}{\~a}o Geral da Atmosfera CPTEC/INPE para o
per{\'{\i}}odo entre 1981-2010. Foi observado que as frentes
frias s{\~a}o mais frequentes na primavera (SON) e no inverno
(JJA), mas a maior precipita{\c{c}}{\~a}o associada ocorre no
ver{\~a}o (DJF) e na primavera (SON). Caracter{\'{\i}}sticas
atmosf{\'e}ricas e a influ{\^e}ncia dos padr{\~o}es de
teleconex{\~a}o foram identificadas para os eventos chuvosos e
secos associadas {\`a} passagem de sistemas frontais. As
principais diferen{\c{c}}as regionais entre os casos chuvosos e
secos s{\~a}o observadas na posi{\c{c}}{\~a}o e intensidade da
baixa press{\~a}o, do cavado frontal e da alta p{\'o}s-frontal,
no gradiente de temperatura e na inclina{\c{c}}{\~a}o da frente.
Nos casos chuvosos durante o ver{\~a}o, o cavado fica bem
amplificado sobre o sudeste e a alta p{\'o}s-frontal {\'e} bem
intensa, enquanto nos casos secos o cavado est{\'a} deslocado
para o oceano. As diferen{\c{c}}as regionais tamb{\'e}m
est{\~a}o associadas ao fluxo de umidade e {\`a}
converg{\^e}ncia sobre a regi{\~a}o estudada. O cavado associado
{\`a} frente fria em superf{\'{\i}}cie {\'e} amplificado
devido {\`a} influ{\^e}ncia das teleconex{\~o}es, como o Modo
Anular Sul (MAS), o padr{\~a}o Pac{\'{\i}}fico-Am{\'e}rica do
Sul (PSA) e o modo Transpolar (TPI). Nos casos chuvosos do
ver{\~a}o, a presen{\c{c}}a da anomalia cicl{\^o}nica sobre
parte do Sul e Sudeste do Brasil e anticicl{\^o}nica no sul da
Am{\'e}rica do Sul associada {\`a} fase negativa dos
{\'{\i}}ndices TPI, MAS e PSA foi um fator importante para
intensificar o cavado frontal e possivelmente dar suporte
din{\^a}mico para a ocorr{\^e}ncia de chuvas intensas. Na
primavera, as circula{\c{c}}{\~o}es cicl{\^o}nica e
anticicl{\^o}nica foram observadas deslocadas para sul em
rela{\c{c}}{\~a}o ao ver{\~a}o nos casos chuvosos, e este
posicionamento est{\'a} relacionado {\`a} fase negativa do TPI e
MAS e positiva do PSA. Nos eventos secos uma ampla {\'a}rea de
anomalia positiva de geopotencial foi observada sobre o Sul e
Sudeste do Brasil. Foi observada a influ{\^e}ncia das anomalias
de baixa frequ{\^e}ncia em fase com as de alta frequ{\^e}ncia
nas caracter{\'{\i}}sticas atmosf{\'e}ricas dos casos chuvosos
e secos no ver{\~a}o. Na primavera, essas anomalias est{\~a}o em
fase nos casos chuvosos, mas fora de fase sobre a regi{\~a}o
frontal, nos casos secos. Nos casos que provocam mais chuva foi
tamb{\'e}m observada {\`a} influ{\^e}ncia da
propaga{\c{c}}{\~a}o de energia desde o oceano Pac{\'{\i}}fico
at{\'e} a Am{\'e}rica do Sul, onde foram identificados
m{\'a}ximos de energia cin{\'e}tica e atividade de
dist{\'u}rbios transientes. As an{\'a}lises com o MCGA mostraram
que o modelo captura as configura{\c{c}}{\~o}es
atmosf{\'e}ricas dos sistemas frontais e reproduz os padr{\~o}es
de teleconex{\~a}o. No entanto, subestima a frequ{\^e}ncia de
frentes frias na primavera e superestima no ver{\~a}o. Foi notada
uma subestimativa no fluxo de umidade, na atividade de
dist{\'u}rbios transientes e na convec{\c{c}}{\~a}o. ABSTRACT:
In this study, frontal systems that cause extreme rainfall (5\%
and 95\% percentile) in an area of southeastern Brazil and the
influence of teleconnections and regional and large scale patterns
were analyzed. This area was chosen due to occurrences of
landslides and flooding during summer and spring. The frontal
systems that cause intense rainfall may contribute to these
disasters and therefore the understanding of the differences
between the rainy and dry events associated with frontal systems
has significant importance. Data from CFSR reanalysis and from the
CPTEC/INPE AGCM were used for the period of 1981 to 2010. The
highest frequency of systems occurs in the spring (SON) and winter
(JJA), but the highest associated precipitation occurs in the
summer (DJF) and spring (SON). Atmospheric characteristics and the
influence of teleconnection patterns were identified for the rainy
and dry events associated with the passage of cold fronts. The
main regional differences between wet and dry episodes were
observed in the position and intensity of the low pressure, the
frontal trough and the post frontal high, in the temperature
gradient and the inclination of the front. In cases of extreme
rainfall during summer, the trough is intensified over the
southeast and the post frontal high is strong. During dry periods,
the trough is displaced to the ocean. The regional differences are
also associated with the humidity flux and convergence over the
analyzed region. The trough associated with the cold front at the
surface is amplified due to the influence of teleconnections such
as the Southern Annular Mode (SAM), Pacific South America (PSA)
and the Transpolar pattern (TPI). For strong precipitation during
summer, a cyclonic anomaly over South and Southeast Brazil and an
anticyclonic anomaly in southern South America associated with the
negative phase of TPI, SAM and PSA indices were important for the
intensification of the frontal trough. This may also give
dynamical support for the occurrence of extreme rainfall. During
spring, the observed cyclonic and anticyclonic circulations were
shifted southward comparing to wet summers. This positioning is
related to the negative phase of the TPI and SAM and positive
phase of PSA in the wet cases. For dry events, a large area of
positive geopotential anomaly was observed over South and
Southeast Brazil. It was noticed an influence of the low frequency
anomalies in phase with the high frequency anomalies in the
atmospheric characteristics for wet and dry events in the summer.
In spring these anomalies are in phase for the wet cases, but out
of phase over the frontal region, in the dry case. In cases of
larger precipitation it was also observed the influence of energy
propagation from the Pacific Ocean to South America, where maximum
kinetic energy and transient activity were identified. Analyses of
the AGCM showed that the model captures the atmospheric
configuration of frontal systems and reproduces the teleconnection
patterns. However, underestimates the cold fronts frequency in the
spring and overestimate in the summer. An underestimation of the
moisture flow, the activity of transient disturbances and the
convection was noted.",
committee = "Seluchi, Marcelo Enrique (presidente) and Cavalcanti, Iracema
Fonseca de Albuquerque (orientadora) and Sansigolo, Cl{\'o}vis
Angeli and Ambrizzi, T{\'e}rcio and M{\"u}ller, Gabriela
Viviana",
englishtitle = "The role of teleconnections and regional factors on the occurrence
of extreme precipitation associated with frontal systems in
Southeastern Brazil.",
language = "pt",
pages = "221",
ibi = "8JMKD3MGP3W34P/3PT6RKP",
url = "http://urlib.net/ibi/8JMKD3MGP3W34P/3PT6RKP",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}