The Role of the Atlantic Ocean in Determining the Recent Multi-Decadal Drought of East Africa

East Africa has been experiencing persistent decline of the March-April-May Long Rains for multiple decades. Although the connection between the decline and the Indo-Pacific Ocean has received much attention the role of the Atlantic Ocean has not been recognized. Here we show the previously unrecognized role of stationary atmospheric wave forms which link the northern Atlantic Ocean basin source region and the East African Long Rains. The Atlantic Multi-decadal Oscillation (AMO) variability dominates the variability during the cessation of the Long Rains (CLR) in May. The negative phase of the AMO is associated with enhanced rainfall during the cessation. In contrast, reduced rainfall occurs during the positive phase of AMO and it has contributed to the ongoing multi-decadal decline. The projected continuation of the positive phase of AMO for several more decades by recent studies imply the likelihood of the Atlantic Ocean's potential contribution to prolong the ongoing drought conditions over East Africa.