The role of ocean dynamics in tropical Pacific SST response to warm climate in a fully coupled GCM

A global coupled ocean-atmosphere GCM forced by a zonally uniform heat flux anomaly in the tropics is used to investigate the role of oceanic dynamics in regulating the tropical Pacific SST response to warm climate. Consistent with earlier CZ model simulations, the GCM simulation demonstrates a La-Nina like response in the tropical Pacific, with the equatorial upwelling playing a dominant role. While the mean upwelling tends to reduce the overall surface warming due to the strengthening of the equatorial thermocline, the anomalous upwelling associated with the strengthening of the easterlies leads to a weak warming in the east. This easterly wind anomaly can be partly attributed to the enhanced equator-subtropical SST gradient which forces a stronger trade wind. Application to global warming is discussed.