A importância relativa do atlântico tropical sul e pacífico leste na variabilidade de precipitação do Nordeste do Brasil

Andreoli, Rita V.; Kayano, Mary Toshie

doi:10.1590/s0102-77862007000100007

Cited by 75 publications

(58 citation statements)

References 26 publications

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“…Rainfall distribution presents strong seasonal modulation, with maximum precipitation between June and July (Table 1; Figure 3B). The pluviometric regime varies significantly throughout the year owing to the El Niño-Southern Oscillation (ENSO) (ANDREOLI; KAYANO, 2007).…”

Section: Study Areamentioning

confidence: 99%

Hydrography and currents on the Pernambuco Continental Shelf

Domingues

Schettini

Truccolo

et al. 2017

RBRH

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The present study presents the seasonal hydrography and currents of the Brazilian Northeast Continental Shelf. The study area is located on the Brazilian tropical coast of the Atlantic Ocean between 7.5 and 9 °S. This continental shelf is narrow (~35 km wide) and shallow, with shelf break lying at a depth of 60 m. Salinity and temperature data were collected monthly by means of hydrographic surveys, conducted across the shelf in a single transect in the central part of the study area, between March 2012 and May 2013. Two further campaigns were also conducted to characterize the winter (August 2013) and the summer (January 2014), covering the whole study area (4,600 km 2 ). Water level and currents were measured using an array of Acoustic Doppler Current Profilers (ADCP) moored at mid-shelf in the central area. Seasonal temperature ranged from 26 °C in September to 29.5 °C in April, with a 2-month lag between the minimum and maximum air temperatures. Salinity did not present a clear seasonal pattern, fluctuating between 36.5 and 37.0 psu throughout the year. The mean temperature and salinity values obtained in the winter and summer campaigns were 26.5 and 27.6 °C and 37.1 and 36.7 psu, respectively. Tropical Water (TW) was predominant, accounting for 95% to 97%, with presence of Coastal Water (CW) limited to the inner part of the shelf. The mean flow velocity values in the water column in winter and summer were 0.11 and 0.06 m/s, respectively, similarly to the seasonal wind regime. Northward currents were observed predominantly in winter, with a short period of inverted southward current. These episodes were related to periods of wind relaxation and presented periodicity of 6-13 days, observed through wavelet analysis. This periodicity may be associated with atmospheric instabilities at higher latitudes. Summer currents were sluggish, when the tides accounted for 75 and 43% of the variance in the cross-and along-shelf current components, respectively. TW is the main water mass in the Pernambuco Continental Shelf (PCS) in summer and winter. Current intensity is weak and without direction in summer and stronger towards the north in winter.Keywords: Water masses; Circulation; Brazilian Northeast Shelf. RESUMOEste trabalho apresenta a descrição sazonal da hidrografia e hidrodinâmica de uma plataforma continental localizada na borda oeste do Atlântico tropical, a área de estudo encontra-se entre as latitudes de 7,5 e 9 °S, possui apenas 35 km de largura e 187 km de extensão, com a quebra de plataforma em 60m de profundidade. A salinidade e temperatura foram coletadas em campanhas hidrográficas mensalmente entre março de 2012 e maio 2013 por meio de transectos na região central da área de estudo. Também, duas campanhas foram realizadas, uma para caracterizar o inverno (Agosto de 2013) e outra o verão (janeiro de 2014) cobrindo toda a área de estudo (4600 km 2 ). O nível da água e correntes também foram coletados com um Perfilado Acústico por efeito Doppler (ADCP) fundeado na região central da área de estudo. A ...

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Section: Study Areamentioning

confidence: 99%

Hydrography and currents on the Pernambuco Continental Shelf

Domingues

Schettini

Truccolo

et al. 2017

RBRH

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“…Average monthly flow rates of up to 3,000 m 3 s -1 (1974) were recorded during the rainy season, while in other years, the average monthly flow rate did not exceed 700 m³/s. This variability is related to large-scale climatic conditions, such as the Southern Oscillation -El Niño and Atlantic Dipole (ANDREOLI; KAYANO, 2007), influencing the position of the Inter-Tropical Convergence Zone. After construction of the weir, the flow was regulated, resulting in a considerable decrease of their maximum values in the annual rainy season.…”

Section: Hydrological Regimementioning

confidence: 99%

Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation

2013

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A B S T R A C TThe Jaguaribe River is the largest semi-arid Brazilian river and represents an important water source for the state of Ceará. The Castanhão Weir, built to regulate the flow of the Jaguaribe, began operating successfully in the 1990s. As a result, the hydrodynamic regime of the estuary has undergone alteration and is no longer subject to the former annual climatological variability of the dry and rainy seasons. This paper introduces an assessment of the changes in the hydrological conditions resulting from the construction of the weir and investigates the structure of the density stratification in the estuary. A field experiment was conducted at the end of the dry season in November 2009, during which salinity and temperature were monitored at different levels for three tidal cycles. The temporal variations in salinity and temperature during the tidal cycles were 16 psu and 1.5°C, respectively. The salinity exhibited a vertical variation of four units, while the temperature variation was much lower. Several stratification indicators were calculated from the observed density: the stratification coefficient, the Brunt-Väisälä frequency and the potential energy anomaly. The results showed that the parameters behave similarly, differences being observed only in their relative magnitudes. The vertical structure of the estuary exhibited marked stratification during the ebb tide but vertical homogeneity during both flood and high tide. With the regularized flow existing under present conditions, the estuary exhibits hyposaline and a partially mixed structure for the period studied, despite the typical expectation of a hypersaline and well-mixed vertical structure. R E S U M OO rio Jaguaribe é o maior rio do semi-árido brasileiro, constituindo uma importante fonte de água para o estado do Ceará. Na década de 1990 entrou em operação o Açude do Castanhão com o objetivo de regularizar a vazão do rio Jaguaribe, o qual obteve grande sucesso. Como consequência foi alterado o regime hidrodinâmico do estuário, o qual atualmente não está mais sujeito a variabilidade climatológica anual de estações seca e chuvosa. O presente trabalho apresenta uma avaliação da mudança do regime hidrológico antes e após a construção do açude, e investiga a estrutura de estratificação da densidade nos estuários. Foi realizado um experimento de campo em novembro de 2009, no fim da estação seca, quando a salinidade e temperatura da água foram monitorados em diferentes níveis durante três ciclos de maré. A variação temporal da salinidade e temperatura durante os ciclos de maré foram de 16 psu e 1,5ºC, respectivamente. A salinidade chegou a apresentar variação vertical de 4 unidades, enquanto que a variação da temperatura foi bem inferior. Foram calculados parâmetros indicadores da estratificação a partir da densidade: coeficiente de estratificação; frequência de Brunt-Väisälä; e a anomalia da energia potencial. Os resultados mostraram que os parâmetros comportam-se da mesma maneira, apenas com diferença da magnitude relativa de seus valo...

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“…Os fatores que influenciam o comportamento da precipitação no NEB são inúmeros, um deles é a variabilidade térmica da superfície dos oceanos, principalmente o Pacífico e o Atlântico, e suas interações com a atmosfera. "Em um estudo pioneiro, Walker (1928) documentou uma notável coincidência do aquecimento anômalo das águas superficiais no Pacífico equatorial e as secas do Nordeste do Brasil" (Andreoli & Kayano, 2007).…”

Section: Introductionunclassified

“…Em anos da fase negativa do dipolo de TSM, estas características são contrárias, consequentemente, as chuvas são frequentes na região (Moura & Shukla, 1981;Nobre & Shukla, 1996). Andreoli & Kayano (2007) constatam que a influência do Atlântico Tropical na variabilidade de precipitação do NEB é mais marcante para a variabilidade de TSM do Atlântico Tropical Sul (ATS), quando comparada com a do Atlântico Tropical Norte (ATN), independente do ENOS. Esse resultado é consistente com os estudos de Moura & Shukla (1981) e Lucena, Servain & Gomes Filho (2011).…”

Section: Introductionunclassified

Downscaling dinâmico de precipitação e veranicos no estado do Ceará

Alves

Silva²,

Rickes³

2017

J. Env. Anal. Progr.

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A B S T R A C TThe semi-arid region of Northeast Brazil (NEB) is known to be an extremely oscillating region from the climatic point of view, due to the temporal and spatial variability of precipitation. The objective of this work was analyzed the internal seasonal and interannual variability of the precipitations, through dry spells, in the State of Ceará. This behavior is directly influenced by the Sea Surface Temperature (SST) of the Pacific and Atlantic oceans. The RSM97 Regional Spectral Model, through the dynamic downscaling technique, was used to quantify variations using dry spells events (consecutive days with rainfall below 2 mm, occurred during the rainy season of the state), from 1974 to 2012, through FUNCEME daily precipitation data, atmospheric numerical model simulations and SST anomalies (ENSO phases). The results were presented in two stages, first diagnostic mode (with SST anomalies observed from 1974 to 2000) and the second prognostic mode (with persistent SST anomalies from 2002 to 2012). It is concluded that the RSM97 model, predicting drought periods during the rainy season, is reasonable, to a great part the results the model underestimated the number of dry spells in relation to those observed, but represented the signal of the observations of the events which indicates that its physical characteristics influenced the quantification of precipitation and its spatial distribution in the state

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A importância relativa do atlântico tropical sul e pacífico leste na variabilidade de precipitação do Nordeste do Brasil

Cited by 75 publications

References 26 publications

Hydrography and currents on the Pernambuco Continental Shelf

Hydrography and currents on the Pernambuco Continental Shelf

Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation

Downscaling dinâmico de precipitação e veranicos no estado do Ceará

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