Fechar
Metadados

@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/rep/8JMKD3MGP3W34P/3PT6RKP",
           targetfile = "publicacao.pdf",
        urlaccessdate = "18 jan. 2021"
}


Fechar