The Meridional and Equatorial Modes of Tropical Atlantic Variability: Related?

The leading interannual modes of Tropical Atlantic SST variability in Spring and Summer - the meridional and equatorial modes, respectively - are shown to be related, with the spring meridional mode leading into equatorial mode with a corresponding phase in summer. For example, if the meridional mode has warm SSTAs in southern tropical basin, the equatorial mode has warm SSTAs along the equator in summer; and vice-versa. It is shown that this modal linkage is not orchestrated by ENSO variability. The relationship between these modes and the variability of June-August African rainfall along the Coast of Guinea is also investigated. The mode relationship enhances the prospects for prediction of boreal summer rainfall over the Coast of Guinea.