Decadal Variability in the North Pacific as Simulated by FGOALS_g Fast Coupled Climate Model

Abstract

AbstractThis study examines the North Pacific decadal‐to‐interdecadal variabilities as simulated by a fast version of the coupled climate model namely FGOALS_g developed at LASG/IAP. The spatio‐temporal structures of those variabilities and the evolution of the dominant mode together with its relation to El Niño‐Southern Oscillation (ENSO) are analyzed with a 300‐yr integration of the coupled model. The results indicate that the model reproduces well many features of the observed North Pacific variability. Similar to that in reality, the simulated modes are characterized by timescales ranging from decades to multidecades. However, the most prominent mode is a bidecadal mode with a principal period roughly 10~20‐yr. The evolution of the bidecadal mode exhibits a clockwise rotation of the upper‐ocean heat content anomalies in an association with the subtropical gyre. The corresponding atmospheric circulation anomalies are associated with the variabilities of Aleutian low, Pacific‐North American (PNA) teleconnection and atmospheric circulation over Eurasia. Both the simulation and the observation show that the North Pacific decadal‐to‐interdecadal variabilities play an important role in modulating the frequency and strength of interannual ENSO events. However, the simulated SST anomalies are fairly larger than that of observations in Kuroshio/Oyashio Extension (KOE) region and Gulf of Alaska. This may be attributed to the excessive sea‐ice coverage error and SST cool biases over high‐latitude in the coupled model.