Seasonal and Interannual Variations of Rainfall over Eastern Northeast Brazil

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  • 1 Instituto Nacional de Pesquisas Espaciais, Sãdo Paulo, Brazil
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Abstract

Using the data for the period 1914–83, rainy and dry season of eastern Northeast (ENF) Brazil are determined. The principal rainy season is April through July (60% of the annual rainfall), and the principal dry season is September through December (10% of the annual rainfall). The fall and winter rains over ENE Brazil are associated with southeasterly winds blowing perpendicular to the coast. The subtropical high in the South Atlantic modulates the strength and direction of winds along the coast that have a determining influence on the interannual variations of rainfall over ENE Brazil.

The possible link between the rainfall over ENE Brazil and SST anomalies in the Atlantic is examined. The SST anomalies of the season January, February, March, April (JFMA) in the southeast Atlantic are positively correlated with the rainfall anomalies of ENE Brazil. The sea surface temperature (SST) anomaly pattern frequently becomes established by January/February over southeast Atlantic suggesting the predictive value of SST anomalies over southeast Atlantic for the rainfall over ENE Brazil.

Abstract

Using the data for the period 1914–83, rainy and dry season of eastern Northeast (ENF) Brazil are determined. The principal rainy season is April through July (60% of the annual rainfall), and the principal dry season is September through December (10% of the annual rainfall). The fall and winter rains over ENE Brazil are associated with southeasterly winds blowing perpendicular to the coast. The subtropical high in the South Atlantic modulates the strength and direction of winds along the coast that have a determining influence on the interannual variations of rainfall over ENE Brazil.

The possible link between the rainfall over ENE Brazil and SST anomalies in the Atlantic is examined. The SST anomalies of the season January, February, March, April (JFMA) in the southeast Atlantic are positively correlated with the rainfall anomalies of ENE Brazil. The sea surface temperature (SST) anomaly pattern frequently becomes established by January/February over southeast Atlantic suggesting the predictive value of SST anomalies over southeast Atlantic for the rainfall over ENE Brazil.

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