TROPICAL-EXTRATROPICAL INTERACTIONS

Abstract

This study examines the links between tropical and subtropical sea surface temperature (SST) anomalies in the Pacific Ocean during ENSO (El Nino-Southern Oscillation) events. A long-term simulation by the UCLA coupled atmosphere-ocean general circulation model is used. It is found that a zonally-oriented SST anomaly dipole in the subtropical Pacific develops almost simultaneously with and is closely related to tropical ENSO events. The dipole is located east of the dateline between 20N and 40N and consists of an anomaly center off the coast of the North America and another anomaly center with opposite sign further to the west. It is demonstrated that this dipole feature is primarily driven by anomalous surface heat fluxes associated with the altered atmospheric circulation during ENSO events.

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