Climate responses in the tropical pacific associated with atlantic warming in recent decades

Abstract

In this study, we investigated the impact of the Atlantic decadal-scale sea surface temperature (SST) variation on the tropical Pacific climate using a Atmospheric General Circulation Model (AGCM). During the recent decade from 2000 to 2010 when the Atlantic SST has sharply increased, observations have shown that the strong easterly and increased precipitation anomalies appeared over the western-central Pacific. It is different from the conventional Gilltype response in which the easterly due to heating in the Atlantic is expected to be extended to the Indian Ocean. We have found that the warm pool over the western Pacific plays an important role in enhancing the atmospheric response to the Atlantic SST forcing in the Pacific basin. Simplified Aqua planet GCM experiments showed that the central location of the anomalous easterly over the Pacific produced by the Atlantic SST forcing highly depends on the location of the idealized warm pool. The reason for this is because the moisture feedback is strongest over the warm pool region, which leads to additional local anomalous convergence, and therefore the easterly produced by the Atlantic SST forcing is enhanced only over the east of the warm pool region.