Statistical Analysis of Trend in Extreme Rainfall and Temperature Events in Parts of North Central States, Nigeria

Abstract

The study investigated trend in extreme rainfall and temperature indices using thirty (30) years daily climatic data from Climatic Prediction Center Merged Analysis of Precipitation (CMAP) for Five stations in the North Central States of Nigeria. Nine (9) extreme rainfall and Five (5) extreme temperature indices developed by Expert Team on Climate Change Detection and Indices (ETCCDI) under the World Meteorological Organization (WMO) were generated using the RClimDex Software. Mann-Kendall, a non-parametric test was used for trend detection while Theil-Sen slope estimator approach was used to examine the magnitude of trend change in the derived indices. Result showed mixed trends of significant and insignificant in the selected extreme indices across the stations. The extreme rainfall indices of Consecutive Dry Days (CDD) and Maximum 1-day rainfall (R1D) showed steady increase across the stations during the study period while the indices of Consecutive Wet Days (CWD) and Number of heavy rainfall days (R10) showed constant decreasing trend across the stations. Further result showed decreasing trend for the extreme temperature indices of Monthly minimum value of daily minimum temperature (TNn) and Diurnal Temperature Range (DTR) across the study area while the other variables showed mixed trend during the same period. The study established that the fluctuating trends in the variables are conceivable indicator of climate change in the study areas. The study recommended that future climate change adaptation strategies should take into account the observed and projected changes in the extremes.

Keywords: Trend, Extreme Climatic Indices, North Central States, Nigeria