@PhDThesis{Ribeiro:2018:LiInSu,
author = "Ribeiro, Bruno Zanetti",
title = "Linhas de instabilidade no Sul do Brasil",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2018",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2018-05-30",
keywords = "linhas de instabilidade, Sul do Brasil, climatologia
sin{\'o}tica, tempo severo, simula{\c{c}}{\~a}o num{\'e}rica,
squall lines, Southern Brazil, synoptic climatology, severe
weather, numerical simulation.",
abstract = "Este estudo mostra uma climatologia de Linhas de Instabilidade
(LIs) no Sul do Brasil. As LIs s{\~a}o identificadas por imagens
de radar, e s{\~a}o classificadas em severas ou n{\~a}o severas
com base em relatos de destrui{\c{c}}{\~a}o causada pelo vento
ou medidas de rajada de vento de pelo menos 80 km h\−1 por
esta{\c{c}}{\~o}es de superf{\'{\i}}cie. Com base nos campos
sin{\'o}ticos em 500 hPa, as LIs s{\~a}o agrupadas em tr{\^e}s
tipos sin{\'o}ticos. Dados da rean{\'a}lise CFSR s{\~a}o
utilizados para produzir compostos do ambiente sin{\'o}tico em
que ocorrem LIs severas e n{\~a}o severas de cada tipo
sin{\'o}tico, al{\'e}m de gerar distribui{\c{c}}{\~o}es
estat{\'{\i}}sticas de par{\^a}metros de tempo severo. Dois
casos de LI severas s{\~a}o simulados com o modelo WRF com
convec{\c{c}}{\~a}o permitida e resolu{\c{c}}{\~a}o de 3 km.
As LIs s{\~a}o mais comuns na primavera, quando tamb{\'e}m
ocorrem os maiores percentuais de LIs severas. A maior parte das
LIs ocorre durante a madrugada e a manh{\~a}, mas o maior
percentual de LI severas {\'e} {\`a} tarde. LIs com deslocamento
mais r{\'a}pido t{\^e}m maior chance de ser severas,
principalmente se o deslocamento for maior que 50 km h\−1.
Os compostos dos campos sin{\'o}ticos mostram que h{\'a}
advec{\c{c}}{\~a}o quente e converg{\^e}ncia do fluxo de
umidade em baixos n{\'{\i}}veis associadas {\`a}s LIs no Sul do
Brasil. A instabilidade termodin{\^a}mica e o DCAPE na
regi{\~a}o s{\~a}o maiores em casos de LI severas de todos os
tipos sin{\'o}ticos. A configura{\c{c}}{\~a}o sin{\'o}tica
mais recorrente quando ocorrem LIs tem como
caracter{\'{\i}}stica um cavado na m{\'e}dia troposfera
corrente acima do Brasil, e os sistemas sin{\'o}ticos s{\~a}o
mais intensos em casos severos desse tipo. Quando o cavado em
m{\'e}dios n{\'{\i}}veis se encontra a oeste dos Andes, os
ambientes associados a LIs severas t{\^e}m como principal
diferencial a maior instabilidade termodin{\^a}mica e maior
DCAPE. LIs que ocorrem em ambientes com predom{\'{\i}}nio de
escoamento zonal na m{\'e}dia troposfera t{\^e}m maior
tend{\^e}ncia de ser severas quanto maior for o cisalhamento do
vento entre 1000 e 500 hPa. Os par{\^a}metros de tempo severo com
maior poder discriminat{\'o}rio da severidade das LIs s{\~a}o o
CAPE e o DCAPE, e o cisalhamento para casos com escoamento zonal.
A simula{\c{c}}{\~a}o num{\'e}rica da LI de 19/10/2014 mostrou
que a vorticidade horizontal no ambiente permitiu a
organiza{\c{c}}{\~a}o da linha convectiva. A
forma{\c{c}}{\~a}o de um v{\'o}rtice meso- e a descida do jato
de retaguarda associada a um eco de arco foram as principais
causas das rajadas de vento severas nesse caso. A LI de
20/12/2014, por outro lado, n{\~a}o esteve associada a um intenso
jato de retaguarda, mas a intensa piscina fria causada pela
precipita{\c{c}}{\~a}o da LI e a forma{\c{c}}{\~a}o de
v{\'o}rtices meso- ao longo da linha convectiva causaram as
rajadas de vento severas. A estrutura de mesoalta e mesobaixas
associada {\`a}s LIs foram muito similares aos modelos
conceituais de LIs assim{\'e}tricas. As distribui{\c{c}}{\~o}es
de flutuabilidade, perturba{\c{c}}{\~a}o de press{\~a}o e
vorticidade horizontal tamb{\'e}m se assemelham aos modelos
conceituais, e confirmam que as LIs no SB t{\^e}m diversas
caracter{\'{\i}}sticas de mesoescala similares {\`a}s que
ocorrem em outros lugares do mundo. ABSTRACT: This study presents
a climatology of squall lines in Southern Brazil. The squall lines
are identified by radar imagery, and classified in severe or
non-severe based on wind-related damage reports or wind gusts of
at least 80 km h\−1 measured by surface stations. Based on
the 500-hPa synoptic fields, the squall lines are grouped in three
synoptic types. CFS Reanalysis data are used to build composites
of the environments where severe and non-severe squall lines under
each synoptic configuration type occur, and generate statistical
distributions of severe thunderstorm parameters. Two significantly
severe squall lines were simulated using the WRF model with
convection-allowing configuration and 3 km of horizontal
resolution. Squall lines are more common during Spring, when the
highest percentages of severe squall lines are also observed. The
majority of the squall lines occur during late night and morning,
but the percentages of severe squall lines are higher in the
afternoon. Squall lines that move faster have higher chance of
being severe, mainly if the squall-line speed exceeds 50 km
h\−1. The synoptic composites show low-level warm advection
and moisture flux convergence are present when squall lines occur
in Southern Brazil. The thermodynamic instability and DCAPE in the
region are higher in severe squall line cases of all synoptic
types. The most recurrent synoptic configuration when squall lines
are observed is characterized by a midlevel trough upstream of
Southern Brazil, and the synoptic systems near the region are more
intense in severe cases of this type. When the midlevel trough is
located west of the Andes, the main differences in severe and
non-severe squall line environments are the thermodynamic
instability and DCAPE. Squall lines occurring under strong zonal
midlevel flow have higher chances of being severe as stronger is
the 1000\−500- hPa wind shear. The severe thunderstorm
parameters with higher discriminatory capacity of the squall lines
severity are CAPE and DCAPE, and the wind shear in cases of zonal
midlevel flow. The 19 October 2014 squall line numerical
simulation showed that horizontal vorticity in the pre-squall line
environment organized the convective line. The formation of a
meso--scale vortex and rear inflow jet descent associated with a
bow echo were the main causes of severe wind gusts in this case.
The 20 December 2014 squall line, on the other hand, was not
associated with an intense rear inflow jet, but the strong cold
pool caused by the squall line precipitation evaporative cooling
and the formation of several meso- -scale vortices along the
convective line were responsible for the severe wind gusts. The
mesohigh and mesolow structures were very similar to conceptual
models of asymmetric squall lines. The distributions of buoyancy,
pressure perturbation and horizontal vorticity are also comparable
to most conceptual models, and confirm that squall lines in
Southern Brazil are similar to squall lines in other parts of the
world.",
committee = "Herdies, Dirceu Luis (presidente) and Seluchi, Marcelo Enrique
(orientador) and Satyamurty, Prakki and Silva Dias, Maria
Assun{\c{c}}{\~a}o Faus da and Nascimento, Ernani de Lima",
englishtitle = "Squall lines in Southern Brazil",
language = "pt",
pages = "253",
ibi = "8JMKD3MGP3W34R/3R2P492",
url = "http://urlib.net/ibi/8JMKD3MGP3W34R/3R2P492",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}