Interação entre padrões pluviométricos na Amazônia Oriental e temperatura da superfície do mar dos oceanos Pacífico e Atlântico Tropicais.

Abstract

The present study aimed to analyze the main climatological patterns of the precipitation in the Eastern Amazon and relate them with the main climatic mechanisms of the Tropical Pacific and Atlantic Oceans. Monthly and annual averages data of precipitation collected in meteorological stations distributed in the Eastern Amazon were used, well as monthly Sea Surface Temperature (SST) anomalies of El Niño areas (Niño 1+2, Niño 3, Niño 3.4 and Niño 4) of Equatorial Pacific Ocean and of Atlantic Dipole. The method of Factorial Analysis in Principal Components (PCA) and Hierarchical Grouping were used to determine the seasonal and spatial patterns and homogeneous groups of the precipitation. The results obtained by PCA showed the existence of three well defined rainfall patterns that explained approximately 92% of the total variance. The dominant pattern defined areas of rainfall that are influenced by the Intertropical Convergence Zone. The second spatial pattern is associated with mesoscale events, such as Instability Lines, that contributes to increase rainfall in the study area in the period of May to August. The third spatial pattern is influenced by performance of the South Atlantic Convergence Zone, an active system acting in late spring and early summer, as well as systems of local scale. Four homogeneous regions were identified and characterized in relation to the seasonal and interannual variations of the precipitation in the Eastern Amazon (Ph1, Ph2, Ph3 and Ph4). The correlation analysis between of the SST anomaly of the El Niño areas and the different homogeneous areas of precipitation in the Amazonian Oriental presented satisfactory results. The rainfall of the regions Ph2, Ph3 and Ph4 are influenced by Equatorial Pacific and South Atlantic Tropical, differently of the region Ph1, under influence of the Equatorial Pacific. The correlation analysis between the SST anomalies of the Tropical Atlantic North and the observed rainfall in the eastern Amazon showed that correlation between such variables was not significant statistically.