Interannual Variability of the Rainy Season and Rainfall in the Brazilian Amazon Basin

Brant Liebmann
NOAA-CIRES Climate Diagnostics Center, Boulder, Colorado

José A. Marengo
Centro de Previsão de Tempo e Estudos Climaticos, INPE, Sao Paulo, Brazil

(Manuscript received 29 January 2001, in final form 15 June 2001)

Abstract

Interannual variability of seasonal rainfall in the Brazilian Amazon basin is examined in context of its relationship to sea surface temperatures in the tropical Pacific and Atlantic oceans. Linear correlations reveal strong relationships, but rainfall patternsare of regional scale. Areas of rainfall exhibiting strong relationships with SST are confined to the equatorial region of the Brazilian Amazon. The best relationships are found either during the season of transition between wet and dry regimes, or entirely within the dry season. It is hypothesized, and results are shown in support, that during the transition seasons, an important contributor to the SST control on seasonal totals is its influence on the timing on the rainy season onset or end. That influence appears to be stronger than the SST influence on the rainy season rain rate.