@InProceedings{PscheidtGrim:2006:InElNi,
author = "Pscheidt, Ieda and Grimm, Alice Marlene",
affiliation = "Universidade de S{\~a}o Paulo, Instituto Astron{\^o}mico,
Geof{\'{\i}}sico e Ci{\^e}ncias Atmosf{\'e}ricas, Departamento
de Ci{\^e}ncias Atmosf{\'e}ricas and Rua do Mat{\~a}o, 1226 -
Cidade Universit{\'a}ria -05508-900- S{\~a}o Paulo - SP, Brasil
(Pscheidt) and Universidade Federal do Paran{\'a}, Departamento
de F{\'{\i}}sica, Centro Polit{\'e}cnico - Campus III - Jardim
das Am{\'e}ricas - 81531-990 - Curitiba- PR, Brasil (Grimm)",
title = "The influence of El Niņo and La Niņa episodes in the occurrence of
extreme precipitation events over Southern Brazil",
booktitle = "Proceedings...",
year = "2006",
editor = "Vera, Carolina and Nobre, Carlos",
pages = "365--370",
organization = "International Conference on Southern Hemisphere Meteorology and
Oceanography, 8. (ICSHMO).",
publisher = "American Meteorological Society (AMS)",
address = "45 Beacon Hill Road, Boston, MA, USA",
keywords = "El-Niņo, extreme events, precipitation, regional analysis,
variability.",
abstract = "El Niņo (EN) and La Niņa (LN) episodes cause impacts in the
precipitation over Southern Brazil. The impact on the frequency of
extreme precipitation events is here regionally analysed. November
is a period with increase of severe rain events in EN and
reduction in LN. During July of the following year also occurs
increase/reduction of extreme events in some areas. The
precipitation and the number of extreme events in homogeneous
areas with respect to significant increase or reduction of severe
rain events show significant correlation with Sea Surface
Temperature (SST) in some regions of the globe, mainly those
affected by El Niņo-Southern Oscilation (ENSO) episodes.
Notwithstanding, lower-frequency variability is also associated
with the variation of these extremes. The variation of the number
of severe rain events between different EN and LN episodes seems
to be associated with the variation of SST in certain regions. The
most recurrent patterns of atmospheric circulation favoring the
occurrence of extreme events are present in extreme events during
both El Niņo and La Niņa episodes, as well as during neutral
years. However, composites of monthly anomalies in EN and LN
years, show that the large-scale favorable conditions for the
occurrence of extreme events appear more during EN than during LN
episodes. This explains the large difference between the frequency
of those events during EN and LN episodes. Composites of anomalies
show differences between EN years with more severe rain events and
EN years with less of these events with respect to neutral years,
mainly in the fields of global SST, vorticity advection at 500
hPa, geopotencial height at 850 hPa, streamfunction at sigma level
0.21 and divergence of vertically integrated moisture flux. These
fields show patterns favorable to precipitation during the years
with increase in the number of extreme events and unfavorable in
years with reduction of these events. During November of EN years
with more severe events than normal there is advection of ciclonic
vorticity over Southern Brazil and positive SST anomaly in the
equatorial East Pacific much more intense than that observed in
years with less extreme events. When there is a reduction of
extreme precipitation events in July of the year following the
onset of an EN episode there are positive anomalies of
geopotencial height at low levels and negative at high levels,
indicating anomalous subsidence. Furthermore, there are
significant negative SST anomalies in the equatorial East Pacific,
while in years with more severe events this does not occurr.",
conference-location = "Foz do Igua{\c{c}}u",
conference-year = "24-28 Apr. 2006",
language = "en",
organisation = "American Meteorological Society (AMS)",
ibi = "cptec.inpe.br/adm_conf/2005/10.24.16.24",
url = "http://urlib.net/ibi/cptec.inpe.br/adm_conf/2005/10.24.16.24",
targetfile = "365-370.pdf",
type = "Climate change in the SH",
urlaccessdate = "11 maio 2024"
}