Both the tropical Pacific and Atlantic host an equatorial mode of interannual variability called the Pacific El Ni¿o and the Atlantic Ni¿o, respectively. Although the Pacific El Ni¿o does not correlate with the Atlantic Ni¿o, anomalous warming or cooling of the two equatorial oceans can form an inter-Pacific-Atlantic sea surface temperature (SST) gradient variability that induces surface zonal wind anomalies over equatorial South America and over some regions of both ocean basins. The zonal wind anomalies act to bridge the interaction of the two ocean basins, reinforcing the inter-Pacific-Atlantic SST gradient through atmospheric Walker circulations and oceanic dynamics. Thus, a positive feedback seems to exist for climate variability of the tropical Pacific-Atlantic Oceans and atmosphere system, in which the inter-basin SST gradient is coupled to the overlying atmospheric wind. Rainfall responds to the inter-Pacific-Atlantic SST gradient by showing an anti-symmetric configuration between the two equatorial oceans, suggesting that rainfall is sensitive to the equatorial inter-basin SST gradient, regardless of which ocean is anomalously warm or cold.