CR 66:201-210 (2015)  -  DOI:

Climatic determinants of March–May rainfall variability over southeastern Ethiopia

Mark R. Jury1,2,*

1Department of Physics, University of Puerto Rico, Mayagüez 00681, Puerto Rico, USA
2University of Zululand, KwaDlangezwa 3886, South Africa
*Corresponding author:

ABSTRACT: Ethiopia southeast of the Rift Valley has 2 wet seasons in boreal spring and autumn. Mar-May rains were statistically analyzed and related to the regional climate. Mean easterly flow from the warm (29°C) southern Indian Ocean rises over the east African escarpment, but convection must overcome the shallow Hadley circulation and dry layer above 600 hPa. Correlation maps at 5 mo lead time contribute 3 predictors to a multivariate algorithm that accounts for 55% of Mar-May rainfall variability. The predictors represent trigger points that suggest a reduction in convection over the east Atlantic Ocean and an increase over the west Indian Ocean. Together, these opposing centers of action alter the circulation and extent of the central African monsoon. Composites of extreme wet and dry seasons reveal the tropical South Atlantic zonal overturning ocean circulation as a determinant of SE Ethiopian Mar-May rainfall. When upwelling strengthens in the Benguela Current, the cold plume sweeps into the Gulf of Guinea, damping convection there. This sets up a velocity potential gradient across the central African monsoon, causing it to expand toward the Rift Valley.

KEY WORDS: Climate prediction · Ethiopia

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Cite this article as: Jury MR (2015) Climatic determinants of March–May rainfall variability over southeastern Ethiopia. Clim Res 66:201-210.

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