Relationships between seasonal rainfall in East Africa and the Southern Oscillation

Abstract

Teleconnections between the Southern Oscillation and seasonal rainfall over East Africa during the period 1923–1984 were investigated using correlation methods. The results from the study indicated significant negative zero lag correlations between Southern Oscillation and seasonal rainfall over parts of East Africa during the months of October—December. Maximum correlations were concentrated along the coast and over some western parts. Peak values in the range — 0.6 were, however, centred along central and northern coastal regions. During the months of July—September significant positive zero lag correlations in the range of 0.5 were observed over some western parts. Low zero lag correlations were, however, obtained over most of the regions with the January—May and annual rainfall records. The computed lagged correlation values displayed characteristics similar to those observed from the zero lag correlations. Highest month to month persistences were again centred within October/November when significant lag correlations persisted for time lags greater than 2 months at some locations. It was, however, noted that although there were some relationships between the Southern Oscillation and seasonal rainfall over parts of East Africa, some of the extreme wet and dry episodes were not related to the Southern Oscillation.