Rainfall Anomalies Pattern in Northwestern Nigeria (NWN)

Abstract

Constant investigation into rainfall anomaly pattern is very crucial as it enables the detection of any departure from normal rainfall condition. When such departure is persistent and statistically significant, it could indicate climate change. This study seeks to investigate anomaly pattern of rainfall in north western Nigeria with the view to determine any extreme departure from established normal rainfall behavior (mean). The study used thirty years (30) rainfall data from 1987 to 2016. The data was obtained from the archives of Nigerian Meteorological Agency (NIMET) for six selected synoptic stations from the region. Purposive sampling technique was adopted in selecting the six synoptic stations given consideration to stations with longer consistent rainfall records. The data was subjected to Standardized Anomalies also known as Standardized Precipitation Index (SPI) to obtain anomaly values. The values were used to plot time series for each station. They were also used to determine the dry or years with drought i.e. negative values and wet or moisture years i.e. positive values. The findings showed that throughout the thirty years period, normal conditions dominated the study area with few pockets of dry conditions. The study concludes that rainfall anomalies pattern in north western Nigeria over the thirty years period under investigation was not too far from normal rainfall conditions.