ENSO and the North Pacific Gyre Oscillation: an integrated view of Pacific decadal dynamics

We show that decadal dynamics of the Pacific Decadal Oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO) are linked through their relationships to ENSO. The PDO and NPGO are the oceanic expression of the two dominant modes of North Pacific atmospheric variability -- the Aleutian Low (AL) and the North Pacific Oscillation (NPO). We compute the two dominant modes of ocean/atmosphere co-variability in the Pacific sector [40S-62N] and find that the first co-variability mode captures the mature phase of ENSO and its atmospheric teleconnections to the AL, while the second co-variability mode captures the NPGO/NPO tropical expression, which leads the ENSO mode by ~8-12 months. The atmospheric projections of these first two modes are used to extract the AL and NPO forcings related to ENSO. These forcings are then integrated with an AR-1 model and lead to skillful reconstructions of the PDO (R=0.65), NPGO (R=0.60), and Pacific surface temperature decadal variance (R=0.4-0.8). We synthesize these results with previous studies and propose a framework for quasi-deterministic decadal oscillations of Pacific climate and for quantifying coherent ecosystem variations along the Pacific boundary currrent systems (e.g. California Current, Gulf of Alaska, Kuroshio and Peru-Chile).