@PhDThesis{Gomes:2023:DiInAn,
author = "Gomes, Mariah Sousa",
title = "Secas em regi{\~o}es da Am{\'e}rica do Sul: diagn{\'o}stico de
intensidade e an{\'a}lise de padr{\~o}es clim{\'a}ticos em
observa{\c{c}}{\~o}es, simula{\c{c}}{\~o}es do clima presente
e proje{\c{c}}{\~o}es futuras de um modelo clim{\'a}tico
global",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2023",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2023-02-10",
keywords = "eventos extremos, seca, sistema clim{\'a}tico, {\'{\i}}ndice de
precipita{\c{c}}{\~a}o padronizado, HadGEM 3, CMIP6, extreme
events, drought, climate system, standardized precipitation
index.",
abstract = "Epis{\'o}dios de seca, embora recorrentes no sistema
clim{\'a}tico, ainda causam graves transtornos do ponto de vista
s{\'o}cio-econ{\^o}mico, afetando o cotidiano da sociedade de
forma geral. Muitos desafios s{\~a}o encontrados no meio
cient{\'{\i}}ficoacad{\^e}mico quanto {\`a}
caracteriza{\c{c}}{\~a}o e identifica{\c{c}}{\~a}o destes
fen{\^o}menos, sendo por vezes subjetiva devido {\`a}
variabilidade em suas evolu{\c{c}}{\~o}es temporal e espacial.
Desta forma, o objetivo geral deste trabalho {\'e} identificar os
padr{\~o}es espaciais de eventos de secas sobre regi{\~o}es
homog{\^e}neas da Am{\'e}rica do Sul, ocorridos entre 1982 e
2019, e realizar uma an{\'a}lise das condi{\c{c}}{\~o}es
atmosf{\'e}ricas em escala regional e global dos mecanismos e
processos f{\'{\i}}sicos associados. O {\'{\I}}ndice de
Precipita{\c{c}}{\~a}o Padronizado (SPI) foi calculado para cada
ponto de grade do continente, e ap{\'o}s, foi aplicada a
An{\'a}lise de Componentes Principais - Modo S, para obter grupos
iniciais com variabilidade de precipita{\c{c}}{\~a}o similar.
Posteriormente, foi aplicado o m{\'e}todo de An{\'a}lise de
Agrupamento N{\~a}o-Hier{\'a}rquico {\`a}s s{\'e}ries de SPI
para os grupos previamente identificados, para determinar as
{\'a}reas homog{\^e}neas. Para cada uma das {\'a}reas
identificadas foram obtidas s{\'e}ries de SPI, para determinar os
per{\'{\i}}odos de seca e respectiva severidade. Visando
discutir os poss{\'{\i}}veis mecanismos causadores dos eventos,
foram analisados os padr{\~o}es de circula{\c{c}}{\~a}o
atmosf{\'e}rica e de outras vari{\'a}veis atmosf{\'e}ricas e
for{\c{c}}ante oce{\^a}nica durante as secas. Eventos secos nas
{\'a}reas homog{\^e}neas identificados em simula{\c{c}}{\~o}es
produzidas pelo modelo HadGEM 3, do CMIP6, para o per{\'{\i}}odo
hist{\'o}rico, foram comparados com os resultados observacionais,
com objetivo de analisar a representa{\c{c}}{\~a}o das
caracter{\'{\i}}sticas das secas pelo modelo. Tamb{\'e}m foram
analisadas as proje{\c{c}}{\~o}es clim{\'a}ticas fornecidas
pelo mesmo modelo, tendo em vista um dos cen{\'a}rios futuros do
CMIP6, identificando desta forma poss{\'{\i}}veis
mudan{\c{c}}as na ocorr{\^e}ncia de eventos de secas na
Am{\'e}rica do Sul. Foram obtidas 3 {\'a}reas homog{\^e}neas
durante o ver{\~a}o, e 4 nas demais esta{\c{c}}{\~o}es do ano.
Essas {\'a}reas compreendem parte do Brasil Central e Sudeste,
Sul do Brasil, Nordeste do Brasil, Amaz{\^o}nia, Uruguai,
Nordeste da Argentina, Paraguai e Bol{\'{\i}}via. A maior parte
dos eventos identificados foi de intensidade moderada, sendo menos
frequentes os severos e extremos. Nas {\'a}reas tropicais houve
maior registro de secas, onde identificou-se tamb{\'e}m uma
tend{\^e}ncia nos {\'u}ltimos anos, de aumento da sua
frequ{\^e}ncia, especialmente durante o inverno, durante a
esta{\c{c}}{\~a}o seca de mon{\c{c}}{\~a}o. Verificou-se que
os eventos registrados sobre as {\'a}reas no norte da
Am{\'e}rica do Sul estiveram associados principalmente ao
aquecimento an{\^o}malo do Pac{\'{\i}}fico Tropical Leste,
gerando subsid{\^e}ncia at{\'{\i}}pica nessas {\'a}reas, sendo
potencializadas por aspectos favor{\'a}veis de grande escala,
como temperaturas superiores {\`a} m{\'e}dia. Os compostos
referentes {\`a}s secas nas {\'a}reas mais a S e SE mostraram a
influ{\^e}ncia de trens de ondas que se propagam do
Pac{\'{\i}}fico Sul at{\'e} o continente, alterando o regime de
circula{\c{c}}{\~a}o e as chuvas. O enfraquecimento do
transporte de umidade da Amaz{\^o}nia para as regi{\~o}es
tamb{\'e}m esteve associado a estes casos. Os centros
an{\^o}malos de geopotencial e linhas de corrente em altos
n{\'{\i}}veis (principalmente sobre o continente) e anomalias de
precipita{\c{c}}{\~a}o foram bem simulados pelo modelo, mas o
padr{\~a}o an{\^o}malo de convec{\c{c}}{\~a}o e TSM n{\~a}o
foi bem representado. A principal mudan{\c{c}}a no futuro {\'e}
de secas mais intensas, verificadas pelas anomalias de
precipita{\c{c}}{\~a}o maiores do que no per{\'{\i}}odo
hist{\'o}rico. Outras diferen{\c{c}}as projetadas para o futuro
pelo modelo, dizem respeito {\`a}s anomalias de temperatura,
tanto do continente quanto do oceano, al{\'e}m das
diferen{\c{c}}as em precipita{\c{c}}{\~a}o. N{\~a}o foram
identificadas diferen{\c{c}}as significativas no n{\'u}mero de
eventos projetados, mas {\'e} importante ressaltar que a
climatologia considerada {\'e} a do clima futuro. ABSTRACT:
Drought episodes, although recurrent in the climate system, still
cause serious socioeconomic disturbances, affecting the daily
lives of society in general. Many challenges are found in the
scientific-academic environment regarding the characterization and
identification of these phenomena, sometimes being subjective due
to the variability in their temporal and spatial evolutions. Thus,
the general objective of this work is to identify the spatial
patterns of dry events over South America, which occurred between
1982 and 2019, and to perform a regional and global analysis of
atmospheric conditions. The Standardized Precipitation Index (SPI)
was calculated for each grid point on the continent, and then
Principal Component Analysis - Mode S was applied to obtain the
initial groups with similar precipitation variability.
Subsequently, the Non- Hierarchical Cluster Analysis method was
applied to the SPI series, to determine the homogeneous areas for
precipitation variability. For each identified areas, SPI series
were calculated to determine the periods of drought and their
severity. The patterns of atmospheric circulation, SST and dynamic
forcing during droughts were analyzed, aiming to discuss the
possible related mechanisms. Finally, the simulations for the
historical period produced by the CMIP6 HadGEM 3 model were
compared with the observed results, in order to verify the
droughts representation by the model. The climate projections
provided by the same model were analyzed, considering one of the
future scenarios of CMIP6, thus identifying possible changes in
the occurrence of dry events in South America. Three homogeneous
areas were obtained during the summer and four in the other
seasons of the year. These areas comprise part of the Center and
Southeast of Brazil, South of Brazil, Northeast of Brazil,
Amazonia, Uruguay, Northeast of Argentina, Paraguay and Bolivia.
Most of the events identified were of moderate intensity, and
severe and extreme events being less frequent. In tropical areas
there was a greater record of droughts, where a trend was also
identified in recent years, towards an increase in their
frequency, especially during the winter, the monsoon dry season.
It was verified that the events registered over the areas in the
north of the SA were mainly associated with the anomalous heating
of the Tropical East Pacific, generating atypical subsidence in
these areas, being potentiated by higher than average
temperatures. The composites referring to droughts in areas
further to the S and SE showed the influence of wave trains
propagating from the South Pacific to the continent, changing the
circulation and rainfall regime. The moisture transport weakening
from the Amazon to the regions was also associated with these
cases. The anomalous geopotential centers and streamlines at high
level (mainly over the continent) and precipitation anomalies were
well simulated by the model, but the anomalous pattern of
convection and SST was not well represented. The main differences
projected for the future by the model concern to the temperature
anomalies, both in the continent and ocean, besides the
precipitation differences. No significant differences were
identified in the number of projected events, but it is important
emphasize that the climatology considered is that of the future
climate.",
committee = "Coelho, Caio Augusto dos Santos (presidente) and Cavalcanti,
Iracema Fonseca de Albuquerque (orientadora) and M{\"u}ller,
Gabriela Viviana (orientadora) and Coelho, Simone Marilene Sievert
da Costa and Reboita, Michelle Sim{\~o}es and Ferraz, Simone
Erotildes Teleginski",
englishtitle = "Droughts in south american regions: intensity diagnosis and
analysis of climate patterns in observations, present climate
simulations, and future projections of a global climate model",
language = "pt",
pages = "199",
ibi = "8JMKD3MGP3W34T/48KJ3US",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/48KJ3US",
targetfile = "publicacao.pdf",
urlaccessdate = "26 abr. 2024"
}