Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Communications Earth and Environment 427 [11 ] ATLANTIQUE AFRIQUE DE L'OUEST AMERIQUE DU SUD BRESIL ZONE TROPICALE 2023 fdi:010088712 ENG Communications Earth and Environment ISI:001109496600001 1 10.1038/s43247-023-01073-0 https://www.documentation.ird.fr/hor/fdi:010088712 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2024-01/010088712.pdf 4 Horizon (IRD) Northeast Brazil and Western Africa are two regions geographically separated by the Atlantic Ocean, both home to vulnerable populations living in semi-arid areas. Atlantic Ocean modes of variability and their interactions with the atmosphere are the main drivers of decadal precipitation in these Atlantic Ocean coastal areas. How these low-frequency modes of variability evolve and interact with each other is key to understanding and predicting decadal precipitation. Here we use the Self-Organizing Maps neural network with different variables to unravel causality between the Atlantic modes of variability and their interactions with the atmosphere. Our study finds an 82% (p<0.05) anti-correlation between decadal rainfall in Northeast Brazil and Western Africa from 1979 to 2005. We also find three multi-decadal cycles: 1870-1920, 1920-1970, and 1970-2019 (satellite era), pointing to a 50-year periodicity governing the sea surface temperature anomalies of Tropical and South Atlantic. Our results demonstrate how Northeast Brazil and Western Africa rainfall anti-correlation was formed in the satellite era and how it might be part of a 50-year cycle from the Tropical and South Atlantic decadal variability. 021 ; 032 UR182 Brésil