Teleconnection between Atlantic Ocean and Local Hydroclimate: Case of Lake Hawassa and Abaya in Ethiopian Rift Valley Basin

Abstract

Large scale atmospheric circulations exist over wide areas that affect regional climate conditions in adjacent or
remote regions. Important aspect of climate change and variability is how these teleconnections are related to
and influence local hydroclimate. In this regard, the hydroclimatic condition of East-Africa has frequently
shown to have teleconnection with Indian and Pacific Oceans with little focus on the influence of Atlantic
Ocean. This study investigated the likely association of Atlantic Ocean with the hydro-climate of two selected
lakes in Ethiopian Rift Valley Basin (Lake Hawassa and Lake Abaya). The study employed three statistical
measure the frequency and strength of the association; and principal component analysis to identify patterns of
variations. The homogeneity test revealed that the water level of Lake Hawassa and Abaya have experienced
significant regime shifts at and around the period in which sea surface temperature (SST) of Atlantic Ocean
significantly shifted. On the other hand, the coherence analysis confirmed that the local hydrology has
significant coherence (p<0.01) with the corresponding sea surface anomalies of Atlantic Ocean. In addition, the
principal component analysis traces out the role of Atlantic Ocean and Indian Ocean to significantly act in the
same direction of influence. The findings provide strong bases to consider sea surface temperature of Atlantic
Ocean as one of the potential predictor of local hydroclimate in East Africa in general and Ethiopia in particular.