The Decadal Variability of the Pacific with the MRI Coupled Models

Abstract

Natural climate variability in the Pacific is one of the most important theme among climate researchers at the Meteorological Research Institute (MRI) in Japan, from a view point of understanding its mechanism and searching predictability for climate around Japan. The institute developed a coupled ocean-atmosphere general circulation model (GCM) (Tokioka et al., 1995), with an emphasis on good representation of natural climate variability especially in the Pacific including El Nino-Southern Oscillation (ENSO). It is shown that ENSO and decadal to interdecadal natural variability in the Pacific are realistically simulated with the coupled GCM (Yukimoto et al., 1996). Analysis of decadal and interdecadal variation of upper ocean and atmosphere revealed in the model may suggest a possible mechanism for such variability. This chapter introduces the spatial and temporal structures of the decadal and interdecadal variability in the Pacific, based on the analysis of MRI model results and observed climate data, and presents some ideas for an inherent mechanism.