Empirical Evidence Linking the Pacific Decadal Precession to Kuroshio Extension Variability

Recent research has revealed a new mode of quasi-decadal climate variability-the Pacific Decadal Precession (PDP)-that has teleconnected impacts upon the state of the ocean and atmosphere across the North Pacific. Previous research has revealed similar decadal scale variability in the location, intensity, and stability of the North Pacific's western boundary current system and in particular the Kuroshio Extension (KE) current, suggesting potential links between the large-scale (1,000 km and larger) ocean/atmosphere variations associated with the PDP and mesoscale (100 km) variations in the KE. Empirical analyses using self-consistent historical state estimates of the ocean and atmosphere over the North Pacific-derived from the 20th Century Reanalysis Version 2c (20CRv2c) and Simple Ocean Data Assimilation - sparse input version 3 (SODAsi.3) data sets for the period 1851-2013-confirm these links exist. Further, these empirical analyses suggest that the PDP both forces and responds to KE variability on decadal time scales. Our synthesis of these empirical results with previously published empirical, theoretical, and numerical results argues for the presence of a self-sustaining decadal oscillation of the ocean/atmosphere system across the extratropical North Pacific in which large-scale ocean-atmosphere coupling positively reinforces the atmospheric circulations that generate KE variability while mesoscale ocean-atmosphere coupling allows the subsequent KE variability to reverse these atmospheric circulations.