Abstract:
The study aims to assess trends in extremes of surface temperature and precipitation through the application of the World
Meteorological Organization’s (WMO) Expert Team on Climate Change Detection and Indices (ETCCDI) on datasets representing
three agroecological zones in Southern Ethiopia. )e indices are applied to daily temperature and precipitation data.
Nonparametric Sen’s slope estimator and Mann–Kendall’s trend tests are used to detect the magnitude and statistical significance
of changes in extreme climate, respectively. All agroecological zones (AEZs) have experienced both positive and negative trends of
change in temperature extremes. Over three decades, warmest days, warmest nights, and coldest nights have shown significantly
increasing trends except in the midland AEZ where warmest days decreased by 0.017°C/year (p < 0.05). Temperature extreme’s
magnitude of change is higher in the highland AEZ and lower in the midland AEZ. )e trend in the daily temperature range shows
statistically significant decrease across AEZs (p < 0.05). A decreasing trend in the cold spell duration indicator was observed in all
AEZs, and the magnitude of change is 0.667 days/year in lowland (p < 0.001), 2.259 days/year in midland, and 1 day/year in
highland (p < 0.05). On the contrary, the number of very wet days revealed a positive trend both in the midland and highland
AEZs (p < 0.05). Overall, it is observed that warm extremes are increasing while cold extremes are decreasing, suggesting
considerable changes in the AEZs.
