@InProceedings{LucioRamConMenMen:2006:ClPrEv,
author = "Lucio, Paulo S{\'e}rgio and Ramos, Andr{\'e}a Malheiros and
Conde, F{\'a}bio Cunha and Mendes, David and Mendes, M{\^o}nica
C.",
affiliation = "{Centro de Geof{\'{\i}}sica de {\'E}vora (CGE)} and Apartado
94, 7000-554 {\'E}vora ? Portugal. (Lucio, Ramos, Conde) and
Faculdade de Ci{\^e}ncias da Universidade de Lisboa - Portugal.
(Mendes, Mendes) and {}",
title = "Climate proxy eventsī patterns and the rainfall variability over
the Brazilian Amazon",
booktitle = "Proceedings...",
year = "2006",
editor = "Vera, Carolina and Nobre, Carlos",
pages = "1545--1553",
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 = "North Atlantic Oscillation, El-Niņo Southern Oscillation,
interanual variability, Intertropical Convergence Zone, Pacific
Decadal Oscillation.",
abstract = "Although the correlation between precipitation in the Brazilian
Amazon and sea surface temperatures (SST) over the Pacific and
Atlantic has been documented since the early twentieth century,
the impact of each ocean variability on the frequency and
intensity of the wet/dry season over Brazilian Amazon and the
underlying mechanisms have remained unclear. The mechanisms of
climate anomalies in the Amazon basin were explored from surface
climatological time series. Interannual variability of seasonal
rainfall in the Brazilian Amazon is examined in context of its
relationship to El-Niņo Southern Oscillation (ENSO), low frequency
phenomena such as the Pacific Decadal Oscillation (PDO) and phases
of the North Atlantic Oscillation (NAO). The regional rainfall has
been related to high-frequency atmospheric phenomena, such as El
Niņo and La Niņa events, of a statistically significant
precipitation anomaly patterns. Non-linear correlations (response)
reveal strong relationships, but rainfall patterns are of regional
scale. Areas of rainfall exhibiting strong relationships with SST
are confined to the equatorial region of the Brazilian Amazon. The
best relationships are found either during the season of
transition between wet and dry regimes, or entirely within the dry
season. It is hypothesized, and results are shown in support, that
during the transition seasons, an important contributor to the SST
control on seasonal totals is its influence on the timing on the
rainy season onset or end. That influence appears to be stronger
than the SST influence on the rainy season. The analysis of
Rainfall variability and sensitivity related to decadal and
long-term anomaly patterns of rainfall has been carried out.
Negative rainfall trends were identified for the entire Amazon
basin, while at the regional level there is a negative trend in
northern Amazonia and positive trend in southern Amazonia. Decadal
time scale variations in rainfall have been discovered, with
periods of relatively drier and wetter conditions, with different
behaviour in northern and southern Amazonia. Spectral analyses
show decadal time scale variations in southern Amazonia, while
northern Amazonia exhibits both interannual and decadal scale
variations. Shifts in the rainfall regime in both sections of the
Amazon basin were identified and changes in the circulation and
oceanic fields suggest an important function of the warming of the
tropical central and eastern Pacific on the decreasing rainfall in
northern Amazonia, due to more frequent and intense El Niņo events
during the relatively dry period. A complementary application was
carried out correlating the rainfall database with the NCEP
Reanalysis dataset. Scenarios for rainy station were considered
consequence of located storms and they are associated with the
Intertropical Convergence Zone (ITCZ) and its seasonal migration.
Preliminary results of this research indicate that the
precipitation over the Amazon Basin presents interanual
variability associated to the ENSO phenomenon, with periodicity of
about 20-25 years in frequency of subtropical highs, probably
associated to the PDO. Besides, we have found strong
anti-correlation, of about 60%, between the Outgoing Long-Wave
Radiation (OLR) and annual cycle of precipitation amount over the
region. There is an apparent association between SST anomalies in
the tropical Atlantic and Pacific and the pentads of onset and end
of the rainy season in the northern and central Amazon.",
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/2005/10.28.13.12",
url = "http://urlib.net/ibi/cptec.inpe.br/adm_conf/2005/10.28.13.12",
targetfile = "1545-1554.pdf",
type = "Understanding long-term climate variations in the SH",
urlaccessdate = "03 maio 2024"
}