The Influence of El -Niño Southern Oscillation (ENSO) Phenomenon on Rainfall Variation in Kaduna Metropolis, Nigeria

Aim and Objectives: The aim of this study is to investigate the influence of El -Niño Southern Oscillation (ENSO) on rainfall variation in Kaduna metropolis from the year 1973-2013.

Study Design: Precipitation data was sourced from NIMET (Kaduna airport) while Sea Surface Temperature Anomaly and Southern Oscillation Index data was acquired from the National Oceanographic Atmospheric Administration (NOAA) climate prediction centre's website.

Methodology: These were analyzed to determine the extent of variation between ENSO and Sea Surface Temperature Anomaly (SSTA) and pattern of change in precipitation during El -Niño and non El -Niño years. Furthermore, the significant difference between rainfall amount of El -Niño and non El -Niño years was also determined.

Results: Results indicated that rainfall within the study area was highly varied during the period studied and there is no direct influence of SOI and SSTA on the rainfall variation in Kaduna metropolis as years considered to be El -Niño years brought about both surplus and deficit rainfall over the years. It was also discovered that the years within both El -Niño and non El -Niño were found to be associated with positive and negative anomalies which signifies surplus and deficit rainfall amounts respectively. The student τ-test indicates that there is no significant difference in rainfall amount of the El -Niño and non El -Niño years within the study period.

Conclusion: From the findings of this study, both the SSTA and ENSO can be inferred to have positive and negative impacts because they caused an increase as well as decrease in rainfall during El -Niño and non El -Niño years within the study area. It was therefore concluded that although ENSO is seen to have impacted on rainfall variability, it does not have direct influence on the total variation within the study area. However, both El -Niño and non El -Niño years show fluctuations in rainfall amount within the study area even though there was no significant difference in rainfall amount between the El -Niño and non El -Niño years within the period of the study.