The North Pacific Oscillation–ENSO and internal atmospheric variability



[1] The relationship between the North Pacific Oscillation (NPO) and El Niño and Southern Oscillation (ENSO) is reexamined using three runs of a coupled general circulation model. The difference in the three simulations is only in the amplitude of internal atmospheric variability felt by the ocean component at the air-sea interface. In observations and a standard coupled model (one AGCM coupled to a single OGCM), the NPO and ENSO may be explained by correlated white noise time series or by two independent red noise time series processes. However, there is the possibility the influence of ENSO could be felt depending on the amplitude of the noise in the North Pacific. When the amplitude of the atmospheric noise is reduced, stronger ENSO variability goes with a stronger ENSO-NPO correlation. The analysis suggests that local North Pacific internal atmospheric dynamics overwhelms the remote influence from ENSO in the coupled model.