ANALYZING VARIABILITY OF RAINFALL LINKAGE WITH ITS TELECONNECTION TO SEA SURFACE TEMPERATURE AND METEOROLOGICAL DROUGHT OVER THE WOLAITA ZONE, ETHIOPIA

Abstract

Rainfall variability is one of the most significant climate variables for global agricultural productivity. It has also effect on the agricultural activities, water and food security over the Wolaita Zone. Station and merged satellite data from 1990 to 2020 and also the two stages of the Coupled Model Intercomparison Project (CMIP6) data to analyze historical (1985 to 2014) and future projected meteorological drought changes from (2041-2100) using two Shared Socioeconomic Pathway (SSP) under SSP2-4.5 and SSP5-8.5 emission scenarios were used in this study. The variability of rainfall at the annual, seasonal, and monthly scales was analyzed by using the coefficient of variation (CV) and standardized rainfall anomalies (SRA) over the study area. The modified Mann-Kendall test was used to determine the upward or downward trend and Sen’s slope estimator was used to determine increasing or decreasing in the magnitude. The correlation analysis was used to show the linkage between sea surface temperatures (SST) with Belg and Kiremt rainfall in the research area. In this study, the power transformation (PT) bias correction method was used to correct the GCM (CMIP6) model data with the observed rainfall dataset serving as a reference. The SPI is the drought index, which indicates historical and future projected meteorological drought conditions at different severity levels that range from normal to extreme drought conditions. The belg rainfall is much more variable than the Kiremt and annual rainfall. During Belg season Indian Ocean Dipole (IOD) is positive or warming and the central Pacific Ocean is warming or during the El Niño phase rainfall increases in amount and distribution. During Kiremt season Indian Ocean Dipole (IOD) is positive or warming and the central Pacific Ocean is cooling or during the La Niña phase rainfall increases in amount and distribution. Future projected meteorological drought will be more affected by extreme and severe drought during the middle and far future under SSP2-4.5 and SSP5-8.5 scenarios, which is more frequent and intense than historical time over the study area. This study provides important guidance for identifying causes, minimizing impacts, and enhancing resilience to droughts over the Wolaita Zone.