A Comparison of Climate Prediction and Simulation over the Tropical Pacific

Abstract This study compares an ensemble of seasonal hindcasts with a multidecadal integration from the same global coupled climate model over the tropical Pacific Ocean. It is shown that the annual mean state of the SST and its variability are different over the tropical Pacific Ocean in the two operating modes of the model. These differences are symptoms of an inherent difference in the physics of coupled air–sea interactions and upper ocean variability. It is argued that in the presence of large coupled model errors and in the absence of coupled data assimilation, the competing and at times additive influence of the initialization and model errors can change the behavior of the air–sea interaction physics and upper ocean dynamics.