Abstract:
ABSTRACT
Rainfall is the total liquid product from the atmosphere. It is the most essential variables which
has a direct and indirect impacts on the environment and human life. Investigations for the variation
of rainfall by different large-scale oceanic impacts are very crucial for the economy and
climatic maintenance of the country. In this work, we investigated the impacts of both ENSO
and NAO on rainfall variability over Ethiopia during 1987-2017 GC. We found significant association
between rain gage rainfall anomaly (RFA) with ENSO and NAO SSTA using 31 years
data of 18 selected stations. The calculated RFA indicates year to year variability of rainfall over
Ethiopia,which lies between 2 and -2. Because of this variability,we applying Person’s correlation
between RFA with SST anomaly of ENSO and NAO. We found that 89%/78% of the selected
stations are negatively/positively correlated with ENSO/NAO. From the correlation coefficient
between RFA at different parts of Ethiopia(Central, Northern, Western, Southern and Eastern)
with SSTA of Nino 3.4 region and NAO, we found that Northern/Southern region is the most
vulnerable by the effect of ENSO/NAO. We also investigated the rainfall anomaly of Ethiopia are
negatively/positively (-0.45/ 0.12) correlated with the SST anomaly of Nino 3.4/NAO. The main
rainy season (kiremit) is highly exposed by the impact of ENSO and SAO (correlation values are 0.67/0.33).
From our analysis, we conclude that ENSO, NAO and SAO have a major contribution
on the rainfall variability of Ethiopia. In addition, when the combination of El Nino and negative
NAO event occurred simultaneously, meteorological drought in Ethiopia is observed. Therefore,
the rainfall distribution over Ethiopia is highly vulnerable by the effect of ENSO except southern
and Eastern part of Ethiopia.