Impact of Trans-Atlantic-Pacific Ocean Dipole-like pattern on summer precipitation variability over West Africa

Recent findings indicate that rainfall variability over West Africa is characterized by more positive anomalies in the last four decades. The authors demonstrate that the recent interannual rainfall variability is linked to an air-sea phenomenon that occurs in the tropical Atlantic and eastern Pacific Ocean, and then propose the Trans-Atlantic-Pacific Ocean Dipole (TAPOD) index as a measure for this tropical ocean phenomenon, which is found to be closely correlated with the West African summer rainfall anomalies. Using observational and reanalysis datasets, composite analysis suggests that enhanced precipitation in West Africa is associated with the positive phase of the TAPOD, which is characterized by warm sea surface temperature anomalies (SSTAs) in the tropical Atlantic and cool SSTAs in the tropical eastern Pacific Ocean. During the positive phase of the TAPOD, there are significant westerly anomalies over the tropical Atlantic Ocean, which drives anomalous water vapor convergence over West Africa, leading to enhanced precipitation in the region.