Decadal prediction of interannual tropical and North Pacific sea surface temperature

The performance of a coupled climate forecast system initialized with observations, relative to the accompanying uninitialized system, to re-forecast annual-mean tropical and North Pacific Sea Surface Temperature (SST) departures at the decadal time scale is described. The study finds that the correlation skill of the leading Empirical Orthogonal Function (EOF) mode of North Pacific SSTs, i.e., the Pacific Decadal Oscillation (PDO), is limited to about one year, while the second mode, i.e., the North Pacific Gyre Oscillation (NPGO), is skillfully forecast throughout the 10-year forecast range. In the tropical Pacific, it is found that the correlation skill of the leading EOF mode of tropical Pacific SSTs, i.e., El Nino Southern Oscillation (ENSO), and the second mode, i.e., ENSO-Modoki, is limited to about two years and one year. A main contributor to forecast skill of the NPGO are the effects of the long-term trend on Pacific SSTs while little impact of the initialization was found.