%0 Journal Article
%@nexthigherunit 8JMKD3MGPCW/43SKC35
%@holdercode {isadg {BR SPINPE} ibi 8JMKD3MGPCW/3DT298S}
%@archivingpolicy denypublisher denyfinaldraft12
%@resumeid
%@resumeid 8JMKD3MGP5W/3C9JHST
%@usergroup Fabia
%@usergroup administrator
%3 Souza_Intraseasonal and submonthly.pdf
%@dissemination WEBSCI; PORTALCAPES; MGA.
%X The precipitation variability over the eastem Amazon (EAM) and northeast Brazil  (NEB) during the autumn rainy season (March to May) is diagnosed using raingauge-based weekly data from 1982 to 2001. Since precipitation in this region is remarkably modulated by, the combined effect of the Pacific and Atlantic Sea Surface Temperature (SST) anomalies, two extreme and contrasting large-scale climatic scenarios are considered in this study. The unfavorable (UNFA V) scenario, defined by the simultaneous occurrences of the El Nino and northward SST gradient in the intertropical Atlantic and the favorable (F AV) scenario, by the concomitant occurrences of the La Nina and southward SST gradient in the intertropical Atlantic. UNF A V (F A V) composites for unfiltered data show remarkable changes in both the Walker and the Hadley cells associated with the Atlantic Intertropical Convergence Zone (ll'CZ) anomalously weakened (enhanced) thus with deficient (abundant) seasonal rainfall in most of the EAM/NEB. The pluviometric variability is objectively identified through EOF analyses performed on the (30-70 day) intraseasonal and submonthly (~ 21 day) filtered week1y precipitation anomalies for 18 autumn seasons (1983 to 2000). The principal components (PC) of the first mode of each analysis show strong oscillations. In particular, the oscillations of the PC series during UNF A V and F A V years reveal that events with anomalously deficient and abundant precipitation over the EAM/NEB occur altemately, even under extreme climatic conditions in the tropical Pacific and Atlantic. Composites based on events with anomalously increased precipitation (objectively selected from the PC series) on intraseasonal and subrnonthly scales are analyzed separately for the UNFA V and FAV years. These analyses showed that for both scenarios the more important rainfall-producing atrnospheric mechanism over the EAM/NEB on intraseasonal scale consists in the establishrnent of deep convective bands trigged by South Atlantic Convergence Zone events or persistent frontal systems over the northeast Brazil. Such a regional pattem is embedded in a large-scale dynamical environment related to the propagation of the Madden-Julian Oscillation over the tropical South Amenca. On the other hand, the main rainfall-producing atmospheric mechanism over the EAM/NEB on submonthly scale is the Atlantic ITCZ during .. FA V years; while a weakened Atlantic ITCZ activity may be forced by meridiona1ly elongated rnidlatitude wave trains at upper troposphere during UNFA V years.
%8 July
%N 3 - 4
%T Intraseasonal and submonthly variability over the Eastern Amazon and Northeast Brazil during the autumn rainy season
%K anomalies, Amazonian, El nino, northeast Brazil, climate variability.
%@secondarytype PRE PI
%@group DMD-INPE-MCT-BR
%@e-mailaddress fabia@cptec.inpe.br
%@copyholder SID/SCD
%@secondarykey INPE-11636-PRE/7017
%@issn 0177-798X
%2 cptec.inpe.br/walmeida/2004/08.13.10.14.05
%@affiliation CPTEC-INPE-Cachoeira Paulista-12630-000-SP-Brasil
%B Theoretical and Applied Climatology
%P 177-191
%4 cptec.inpe.br/walmeida/2004/08.13.10.14
%D 2005
%V 81
%A Souza, Eve B.,
%A Kayano, Mary Toshie,
%A Ambrizzi, Tercio,
%@area MET