Teleconnections Between South America and Western Africa as Revealed by Monthly Precipitation Analyses

摘要

The spatial distribution of monthly precipitation deviations from the normal over tropical South America and Western Africa was investigated using the available data up to the seventies. The spatial scales associated with these deviations were determined for dry and wet years in Norhteast Brazil. It was found that, on the average, the NE Brazil drought spatial scale is not confined to that region but extends from South America to Africa, and perhaps more to East, in accordance with GCM simulations by Moura and Shukla (1981). The results also show an inverse relationship between NE Brazil and Guyanas rainfall, in agreement with Hastenrath and Heller (1977). It was found that years of drought in NE Brazil are also extremely dry over the south equatorial region of Africa, west of 20 deg E. In addition, time series of seal level wind divergence for March in the Atlantic, from 1948 up to 1972, correlated with precipitation in NE Brazil (Fortaleza and Quixeramobim) shows a negative area of correlation in South Atlantic and a positive area in tropical North Atlantic.