Study of the PDO Index Predictability for 1 to 5 Years with INMCM5

The Pacific Decadal Oscillation (PDO) index has been calculated using the INMCM5 climate model developed by the Marchuk Institute of Numerical Mathematics, Russian Academy of Sciences. The PDO index correlation with the reanalysis data decreases from about 1.0 in November of the starting year to 0.355 in October of the following year. The model forecast for the PDO index is reliable for the first 2 years, but correlation coefficients decline significantly after that. The inertial forecast is more accurate in the first 2 years and becomes less reliable onward. The correlation coefficient for the model ensemble forecast of the PDO index with its components in the ensemble is greater than the correlation between the ensemble average and the actual PDO index. The INMCM5 climate model is suggested to have potential for considerable improvement in forecasting the PDO.