Combined Impact of Indian Ocean Dipole and El Niño Southern Oscillation Features on Drought Over Southeast Ethiopia
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Date
2024-06
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Addis Ababa University
Abstract
Several studies have revealed that ENSO and IOD teleconnections significantly impact drought Thus, understanding these impacts is critical for expressing effective adaptation and mitigation strategies. Specifically, the combined effects of El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) SSTs on drought events throughout the primary rainy season (February–May) over southeast Ethiopia are the focus of this thesis. For the analysis, we used historical climate data for the period spanning 1992–2022, ENSO, and IOD data. The data used to examine the relationship among the different indices with drought using the statistical analysis method. Therefore, the Thornthwaite method used to calculate SPI-3, and Pearson correlation was applied to identify the association between different phases of ENSO/IOD and drought. The characteristic analysis depicts that the study area had a long duration, frequent intensity, and moderate to extreme drought severity from 1992 to 2022. Accordingly, the results show that the combined occurrence of ENSO and IOD (El Niño/pIOD) enhanced the rainfall, thus reducing the occurrence of drought events. In contrast, the independent occurrence of pure El Niño, pure La Niña, and pure positive IOD, where their corresponding indices phases were neutral, were associated with drought events. These findings' implications highlight how crucial it is to include climate teleconnections like pure La Niña and pure El Niño; pure positive IOD association with drought, which is important to drought monitoring and seasonal climate outlook preparation for Southeast Ethiopia.
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Keywords
ENSO, IOD, SPI, Rainfall, Drought, Southeast Ethiopia