Date and time: 
Mon, 2015-11-30 15:02
Location / Venue: 


Global oceans continually interact with the atmosphere in complex non-linear feedback processes referred to as coupling. The drag of winds on the ocean surface induces ocean waves and changes in sea surface temperatures, which subsequently generate pressure gradients that govern the atmospheric motions. Changes in ocean temperatures over the Pacific Ocean sometimes coincide with higher or lower than normal ocean temperatures over the Indian Ocean and altered atmospheric systems, which is referred to as the El Niño-Southern Oscillation (ENSO) phenomenon. These complex interactions between distant places are termed as teleconnections.

For El Niño to influence the rainfall over East Africa, its occurrence should be in agreement with the Inter-tropical Convergence Zone (ITCZ) and many other systems that control the weather over the region. More often than not, warm south-eastern Pacific Ocean temperatures (El Niño) are associated with warm waters in the western Indian Ocean near the coast of East Africa. When the warming of the western Indian Ocean is accompanied by cooler ocean temperatures in the eastern Indian Ocean (near the Indonesia/Malaysia maritime continent), this phenomenon is referred to as the Indian Ocean Dipole (IOD). A well-developed IOD was associated with heavier than normal rains over East Africa in 1961, 1977, and 1997; but 1961 was in fact an ENSO neutral year (i.e., neither El Niño nor La Nina, the antithesis of El Niño)!

El Niño does not necessarily translate into heavy rainfall for the entire equatorial East Africa region (Ogallo, 1994).

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Expiry Date: 
Sat, 2080-11-30 15:02