POSSIBLE TELECONNECTION BETWEEN THE INDIAN OCEAN DIPOLE (IOD) AND RAINFALL DISTRIBUTION OVER NIGERIA

Abstract

The El Nino Southern Oscillation (ENSO) has some level of control over the weather of Nigeria and Africa seasonally but there has been enough debate as to the extent of the control. ENSO magnitudes do not necessarily translate into impacts in the same direction hence, attempt to investigate possible teleconnections with the Indian Ocean Dipole Mode Index (IODMI) phases over equatorial Indian Ocean that could explain the subsisting gaps in the knowledge of large scale controls on Nigerian Monsoon Seasonal Rainfall (NMSR) pattern is the basis of this paper. Daily rainfall data was obtained from Nigerian Meteorological Agency (NiMet) and Sea Surface Temperatures (SSTs) over the Indian Ocean and the Pacific Ocean were obtained from National Oceanic and Atmospheric Administration (NOAA) site for a period of 1983-2015. Pearson correlation coefficient method was used to assess the spatial and temporal relationship between the IODMI/NMSR and ENSO/NMSR while the test-of-significance of the correlation results were carried out using two methods- Critical r value and p-value. The results revealed that there is a significant correlation at alpha value 0.1 between the IODMI and NMSR over the selected stations with contrasting tendencies to increase rainfall at a certain period of the year or decrease it at another period. However, the comparison of the influence of IODMI and ENSO indices negates their effects on NMSR which is dependent on the strength of correlation, thus with both having a decreasing north to south spatial pattern. Hence, the study concluded that there is a teleconnection between the NMSR and IODMI over the stations considered in the study and it is recommended that the incorporation of IODMI for the climate prediction of the monsoon rainfall over Nigeria would improve the resilience of different specific sectors of the economy especially agriculture.