KUDAKWASHE KELVIN CHIKUKWA R169999D THE RELATIONSHIP BETWEEN EL NINO AND THE SOUTHERN OSCILLATION AND HOW IT AFFECTS ZIMBABWE SUMMER RAINFALL KUDAKWASHE KELVIN CHIKUKWA R169999D

ENSO The El Niño-Southern Oscillation (ENSO) is a naturally occurring phenomenon that involves fluctuating ocean temperatures in the equatorial Pacific. The warmer waters essentially slosh, or oscillate, back and forth across the Pacific, much like water in a bath tub. El Niño-Southern Oscillation (ENSO) is a global coupled ocean-atmosphere phenomenon. The Pacific ocean signatures, El Niño and La Niña are major temperature fluctuations in surface waters of the tropical Eastern Pacific Ocean.

SOUTHERN OSCILLATION the periodic change in the pressure differential between the Southeastern Pacific high pressure and the Western Pacific equatorial low pressure that occurs in concert with the El-Nino-Southern Oscillation events The atmospheric signature, the Southern Oscillation (SO) reflects the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.

EL NINO a southerly flowing warm current that generally develops off the coast of Ecuador around Christmas time. Occasionally it will move feather south into Peruvian coastal waters and cause the widespread death of plankton, fish, and other organisms dependent upon fish for food (NOT an atmospheric event)

El Niño/Southern Oscillation (ENSO) A shift in the normal relationship between the atmosphere and ocean in the tropical Pacific Ocean. Normally, strong winds (trade winds) blow to the west in the Pacific, moving warmer surface water away from North and South America. Simultaneously, cold water from the ocean depths rises to the surface off the west coast of South America. This upwelling brings nutrients to the surface, supporting fisheries and ecosystems in the area. In an El Niño event, these trade winds die down, causing warmer surface water to accumulate off western North and South America. This leads to increased rainfall, storm activity, and flooding in the Americas (especially the southwestern United States and Peru) and drought conditions in Australia and other areas in the western Pacific and the Indian Ocean.

Typical El Niño Effects: December Through February

RELATIONSHIP WITH ZIMBABWE Pair‒wise correlations are found between Zimbabwe summer rainfall and SST in the central Indian Ocean (r<−0·5) in austral spring. Below normal OLR values in September over southern Africa corresponds with good rains in the following summer. Rainfall–upper‒wind correlations are optimum (r<−0·7) over the equatorial Atlantic in spring. Predictability of Zimbabwe summer rainfall. Available from: https://www.researchgate.net/publication/229796982_Pr edictability_of_Zimbabwe_summer_rainfall [accessed Oct 29 2017].

RELATIONSHIP WITH ZIMBABWE (cont.) The global SST changes associated with the El Niño- Southern Oscillation (ENSO) phenomenon are one of the major signals for seasonal rainfall variability in Zimbabwe (Mushore, 2013b). Statistically significant lead-lag relationships between summer rainfall and selected air/sea features have been documented (Makarau and Jury, 1997; Rocha and Simmonds, 1997; Manatsa and Behera, 2013). On the other hand, other studies have concluded that notable variations in rainfall amount as well as temporal and spatial distribution occur in Zimbabwe between the opposite extremes in the phase of the ENSO (Matarira, 1990).