Influence of the November Arctic Oscillation on the subsequent tropical Pacific sea surface temperature

Previous studies suggested that the variability of boreal spring Arctic Oscillation (AO) can exert a significant influence on the sea surface temperature (SST) anomalies in the Nino-3.4 region during the following winter. This study further reveals that AO in November can have a pronounced influence on the tropical central-eastern Pacific SST anomalies during the following spring and summer. When the November AO is in its positive (negative) phase, SST anomalies tend to be positive (negative) during the following spring and summer in the tropical central-eastern Pacific. The influence of the AO is accomplished by atmospheric circulation anomalies over the subtropical North Pacific through an interaction between the synoptic-scale eddy and the low-frequency mean flow. In the positive November AO years, pronounced cyclonic circulation and atmospheric heating anomalies are observed over the subtropical North Pacific. The atmospheric heating anomalies sustain westerly wind anomalies over the tropical western North Pacific through a Gill-like atmospheric response. The westerly wind anomalies extend eastward subsequently through positive air-sea feedback mechanism, and result in SST warming during the following spring and summer in the tropical central-eastern Pacific. Results of this study imply that the November AO index can be used as an effective predictor of SST anomalies in the Nino-3.4 region during the following spring and summer.