@InProceedings{GrimmFlacTede:2010:ENExRa,
author = "Grimm, A M and Flach, R A and Tedeschi, Renata Gon{\c{c}}alves",
affiliation = "Physics, Universidade Federal do Paran{\'a}, Curitiba, Brazil and
Physics, Universidade Federal do Paran{\'a}, Curitiba, Brazil and
{Instituto Nacional de Pesquisas Espaciais (INPE)}",
title = "ENSO and extreme rainfall events in present and future climate in
South America",
booktitle = "Abstracts...",
year = "2010",
organization = "The Meeting of the Americas.",
keywords = "Extreme events, climate change and variability, precipitation,
ENSO.",
abstract = "Analysis with observed data shows a clear association between ENSO
(El Niņo / La Niņa) episodes and the frequency of extreme rainfall
events over South America. ENSO is the main source of interannual
variability in South America, and its influence varies throughout
the annual cycle. For instance, in austral spring (November) it is
very significant in southeastern South America, producing increase
(decrease) of extreme events in the La Plata Basin during El Niņo
(EN) (La Niņa, LN) episodes. In peak summer monsoon season
(January), the extreme events in Central-East South America, in
the South Atlantic Convergence Zone and in the core monsoon region
are enhanced (hampered) during EN (LN) episodes. In austral autumn
(April), there is significant enhancement of extreme events in the
La Plata Basin during EN episodes, while at the same time of LN
episodes the frequency of extreme events is increased in Northeast
Brazil. These significant changes in extremes are much more
extensive than the corresponding changes in monthly rainfall,
because the highest sensitivity to ENSO is in the extreme range of
daily precipitation. The ENSO-related changes in the frequency of
extreme rainfall are important, since the most dramatic
consequences of climate variability result from changes in extreme
events. Therefore, an important issue is the assessment of the
impact of global anthropogenic climate change on ENSO and its
impact on extreme rainfall in South America. Possible future
changes in the influence of ENSO on the frequency of extreme
precipitation events in South America are analyzed through the
outputs of the coupled model ECHAM5-OM for the twentieth century
climate (1960-2000), and the future climate scenario SRES-A2
(2060-2100). Extreme events are defined as three-day mean
precipitation above the 90th percentile. The EN and LN years in
the model output are determined from the Niņo 3 SST anomalies (as
in the observations), and verified against the extreme phases of
the ENSO mode of SST variability, for both periods. The model
reproduces well the strongest observed impacts of ENSO in the
present climate, although not all their features. The areas with
consistent impact on the frequency of extreme events are generally
extended in the future climate, and the ENSO-related frequency is
enhanced with respect to the present in several instances, such as
the spring in southeastern South America (La Plata Basin). Also
the shifts produced in the daily rainfall distributions, with
respect to present climate during EN, LN and all years are
examined. In southern Brazil, for instance, the probability of
light rainfall in spring is reduced, while it increases in the
heavy rainfall tail of the frequency distributions.",
conference-location = "Foz do Igua{\c{c}}u, BR",
conference-year = "08-12 aug 2010",
language = "en",
urlaccessdate = "2024, May 19"
}