Evaluation and projection of the AMO and PDO variabilities in the CMIP5 models under different warming scenarios part1: Evaluation

Abstract

The capabilities of the CMIP5 models to simulate the two most important interdecadal modes, the Atlantic Multi-decadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO), are evaluated by comparing the observed sea surface temperature data from 1880 to 2009 and the CMIP5 simulations under the historical scenario. The multi-model ensemble (MME) historical simulations show deficiency in reproducing characteristics of the PDO mode in the tropics but well simulated the spatial patterns of the AMO and PDO in the high latitudes. The amplitude of the two modes is obviously weaker in the historical simulations than the observation. In terms of periodic simulations, the MME can simulate the 60–70 year period of the AMO and the double periods, namely 20 and 60–70 years, of the PDO. The MME show more realistic simulations of observed spatial and temporal features of AMO and PDO than most models. The CESM1-CAM5, FGOALS-g2, GISS-E2-R-CC, GISS-E2-H-CC and MIROC-ESM-CHEM are the top-performing models. By comparing the individual models, the variances of the AMO and PDO modes decrease when the simulated global mean sea surface temperatures are higher.