Abstract

Pacific Decadal Oscillation (PDO) is characterized by climatic shifts centered in the North Pacific. Some studies suggest this variability results from the interactions between tropical and extratropical Pacific Oceans. Other studies argue that the decadal variability can be excited by the coupled atmosphere-ocean system over the extratropical North Pacific, without interacting with the tropical Pacific Ocean. It has also been suggested that PDO may contribute to decadal changes in ENSO activity. At least two different modulation mechanisms have been proposed. One emphasizes the existence of shallow ocean pathway that allows PDO to influence ENSO activity through ocean subduction. The other argues the decadal-scale variations in the atmospheric general circulation over the Northern Pacific can extend to the tropics. The slow changes in the trade wind system precondition the mean state of the thermocline in the equatorial ocean, which leads to prolonged periods of enhanced or reduced ENSO activity. We explore those hypotheses of generation and modulation mechanisms by examining the air-sea interactions associated with PDO in CGCM simulations.

Related Publications