@MastersThesis{Coutinho:2008:VaCl,
author = "Coutinho, Michelyne Duarte Leal",
title = "M{\'e}todo objetivo de identifica{\c{c}}{\~a}o dos
v{\'o}rtices cicl{\^o}nicos de altos n{\'{\i}}veis na
regi{\~a}o tropical sul: valida{\c{c}}{\~a}o e climatologia",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2008",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2008-11-10",
keywords = "v{\'o}rtice cicl{\^o}nico de altos
n{\'{\i}}veis/upper-tropospheric cyclonic vortex, m{\'e}todo
objetivo/objective method, regi{\~a}o Tropical Sul/South Tropical
region, valida{\c{c}}{\~a}o/validation,
climatologia/climatology.",
abstract = "Um M{\'e}todo Objetivo (MO) foi desenvolvido para identificar
V{\'o}rtice Cicl{\^o}nico de Altos N{\'{\i}}veis (VCAN) na
regi{\~a}o Tropical Sul, baseado na vorticidade relativa e no
escoamento horizontal do vento ao redor do centro dos sistemas.
Esses sistemas sin{\'o}ticos apresentam um movimento irregular
que tornam as previs{\~o}es de tempo complexas. O estudo da
variabilidade interanual e intrasazonal das principais
caracter{\'{\i}}sticas (n{\'u}mero de ocorr{\^e}ncia,
per{\'{\i}}odo de vida, intensidade e regi{\~a}o de
forma{\c{c}}{\~a}o) dos v{\'o}rtices foi feito atrav{\'e}s de
uma climatologia de 28 anos (1979-2006) com os resultados obtidos
pelo MO. O deslocamento e os mecanismos de forma{\c{c}}{\~a}o
foram analisados para casos selecionados. Foram identificados 886
v{\'o}rtices, em que 75,3% perduraram de 2 a 4 dias. O
n{\'u}mero de v{\'o}rtices diminuiu {\`a} medida que o
per{\'{\i}}odo de vida aumentou. No ver{\~a}o, foi encontrado o
maior n{\'u}mero de VCAN e no inverno o menor. Dos 14
per{\'{\i}}odos avaliados da climatologia com eventos de El Niņo
(9 per{\'{\i}}odos) e La Niņa (5 per{\'{\i}}odos), foi
verificado em 5 per{\'{\i}}odos com El Niņo, maior n{\'u}mero
de v{\'o}rtices moderados e em 3 per{\'{\i}}odos com La Niņa,
maior n{\'u}mero de v{\'o}rtices fracos. A regi{\~a}o
preferencial de ocorr{\^e}ncia do VCAN {\'e} no norte do Oceano
Atl{\^a}ntico Sul com 603 casos dos 886 contabilizados nos 28
anos, no entanto a {\'a}rea continental com maior
forma{\c{c}}{\~a}o desse sistema {\'e} no NEB com 141 casos. A
instabilidade barotr{\'o}pica foi verificada como mecanismo de
forma{\c{c}}{\~a}o nos dois v{\'o}rtices selecionados. Foi
verificado tamb{\'e}m que a componente zonal do vento mais
intensa na regi{\~a}o subtropical possibilitou a
forma{\c{c}}{\~a}o de um maior n{\'u}mero de VCAN na
regi{\~a}o equatorial, com contribui{\c{c}}{\~a}o do aumento do
n{\'u}mero de v{\'o}rtices intensos. Este aumento contribuiu na
s{\'e}rie climatol{\'o}gica do n{\'u}mero total de
v{\'o}rtices para uma tend{\^e}ncia crescente e significativa a
partir de 2003. O deslocamento de um VCAN foi analisado usando a
equa{\c{c}}{\~a}o da vorticidade. Durante os dois primeiros dias
do per{\'{\i}}odo de vida deste, houve maior
contribui{\c{c}}{\~a}o do termo de diverg{\^e}ncia horizontal,
no meio deste per{\'{\i}}odo, observou-se
contribui{\c{c}}{\~a}o significativa do termo de
advec{\c{c}}{\~a}o horizontal de vorticidade relativa, j{\'a} o
termo de advec{\c{c}}{\~a}o horizontal de vorticidade
planet{\'a}ria apresentou contribui{\c{c}}{\~a}o ao longo do
per{\'{\i}}odo. ABSTRACT: An Objective Method (OM) to identify
Upper-Tropospheric Cyclonic Vortex (UTCV) in South Tropical region
was developed based on relative vorticity and on horizontal flow
of the wind round the centre of the system. As this synoptic
system shows an irregular movement the weather forecasts become
complex. The interannual and intrasazonal variability study of the
main characteristics (occurrence number, life period, intensity
and region of formation) of the UTCV was made through climatology
of 28 year (1979 2006) with the results obtained from OM. The
displacement and formation mechanisms were analyzed from the
selected cases. 886 vortices were identified, in which 75,3% of
the cases had duration from 2 to 4 days. The number of vortices
decreased when the life period increased. In summer, a greater
number of UTCV and in the winter a reduced number of cases were
found. Of the 14 analyzed climatology periods of El Niņo (9
periods) and La Niņa (5 periods) events, a greater number of
moderate vortices was verified in 5 El Niņo periods and greater
number of weak vortices in 3 La Niņa periods. The main region of
UTCV occurrence was observed over the north region of the South
Atlantic Ocean with 603 cases of the 886 founded in the 28 years.
The continental area with higher number of case formations was
Northeastern Brazil with 141 cases. The barotropic instability was
verified as a formation mechanism in 2 selected vortices. A strong
zonal wind over the subtropical region that contributed with a
greater number of UTCV formations and with intense vortices over
the Equatorial region was also verified. The increase of number
intense vortex contributed to positive significant trend of total
vortices number from 2003 year. The displacement a UTCV was also
analyzed using the vorticity equation. During the period of life
in the first 2 days the horizontal divergence term had the highest
contribution. During the middle of this period, the horizontal
advection term of relative vorticity had a significant
contribution. The planetary horizontal advection term, presented a
contribution during the period.",
committee = "Ferreira, Nelson Jesus (presidente) and Gan, Manoel Alonso
(orientador) and Camargo, Ricardo de",
copyholder = "SID/SCD",
englishtitle = "Objective method identification upper-tropospheric cyclonic
vortices in the South Tropical region: validation and
climatology",
language = "pt",
pages = "119",
ibi = "8JMKD3MGP8W/348MD2H",
url = "http://urlib.net/ibi/8JMKD3MGP8W/348MD2H",
targetfile = "paginadeacesso.html",
urlaccessdate = "02 maio 2024"
}