Enhanced Seasonal Predictability of the Arctic Oscillation and the Role of the Sea Surface Temperature Forcing

This study assesses the skill of boreal winter Arctic Oscillation (AO) predictions with state-of-the-art dynamical ensemble prediction systems (EPSs): GloSea4, CFSv2, GEOS-5, CanCM3, CanCM4, and CM2.1. The skill of AO forecasts during the recent period (1997–2010) is higher than that of the earlier period (1983–1996), suggesting change of potential predictability. Observation shows intensified teleconnection between the AO and the El Niño and Southern Oscillation (ENSO) after mid-1990s. The recent intensification is associated with low frequency Pacific SST variability such as the Interdecadal Pacific Oscillation (IPO) and the North Pacific Gyre Oscillation (NPGO). The observed teleconnection between the tropics and the extra-tropics has intensified nonlinearly in the ENSO-NPGO out of phase years.