TITLE:
Extreme Rainfall Events over the Amazon Basin Produce Significant Quantities of Rain Relative to the Rainfall Climatology
AUTHORS:
Adriane Lima Brito, José Augusto Paixão Veiga, Marcos Cezar Yoshida
KEYWORDS:
Extreme Rainfall Events; Climatology; Amazon
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.4 No.2,
April
10,
2014
ABSTRACT:
Although much effort has
been made to characterize and understand extreme rainfall’s causes and effects,
little is known about their frequency and intensity. Moreover, knowledge about
their contribution to the total rainfall climatology is still minimal,
especially over the Amazon where rainfall data are very scarce. In this paper
we propose to classify extreme rainfall events by type and analyze their
frequency and intensity over South America with a focus on the Amazon basin.
Gridded daily data from the MERGE/CPTEC product over a period of 15 years
(1998–2013) was used. An adaptation of Rx5d climate index was applied to select different kinds
of extreme rainfall for the purpose of quantifying their frequency and
intensity as well as their contribution to the accumulated rainfall
climatology. According to the results, all kinds of extreme rainfall events can
be observed over the studied area. However, the quantity of rainfall produced
by each type is different, and consequently their percent contributions to the
total accumulated rainfall climatology also differ. For example: in the Amazon
region EET-I is responsible for 15% - 40%
of the total accumulated rainfall. Moreover, in the Brazilian northeast there
are regions where EET-I exceeds 40% of the total rainfall. In northeast Brazil
EET-II is responsible up to 30% of the total accumulated rainfall. EET-III is
responsible for 5% - 15% in the
Amazon basin, 25% - 45% in
northeast Brazil and 10% - 45%
over Roraima State. Area-mean time variation shows that the quantity of
rainfall extremes over the Amazon basin was reduced during the El Nino years of
2002, 2005, 2007 and 2010, while during the La Ni?a episodes of 1999, 2008 and
2011 the quantity of rainfall related to the extremes increased.