Empirical Evidence Linking the Pacific Decadal Precession to Kuroshio Extension Variability

Abstract

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.

The Pacific Decadal Precession and its Relationship to Tropical Pacific Decadal Variability in CMIP6 Models

“…Therefore how the PDP is placed within this paradigm requires further research. For example, relationships between the PDP and other climate modes in the Pacific, including the Madden-Julian Osciallation, variability in the Kuroshio-Oyoshio Current (Anderson, 2019), and the meridional modes, need to be quantified. One particular link to the PDP yet to be explored is the connections between the PDP and the NPGO.…”

“…showing that the N-S phase of the PDP maps onto the NPO and the concomitant SSTa evolution in the tropics related to CP ENSO, which is a forcing for the NPO (Furtado et al, 2012), there is likely a link between the PDP and the NPGO on the quasi-decadal timescale. Furthermore, SSTa in the North Pacific can substantially impact the overlying circulation (Frankignoul and Sennéchael, 2007), so the underlying North Pacific SSTa field may influence the evolution of the PDP as well (Anderson, 2019).…”

Enhanced interactions of Kuroshio Extension with tropical Pacific in a changing climate

“…( a ) Power Spectrum as a function of the SSH-based KE index period (year) from the observations and HRC with 95% significance levels. ( b ) Internal air-sea coupled KE system (KE → KE downstream response → PDO/ NPGO → KE, hypothesis 1 17 ), Pacific Decadal Precession KE system (KE → north–south teleconnection phase → east–west teleconnection phase → KE, hypothesis 2 19 , and extratropical-tropical coupled KE system (KE → KE downstream response → PMM/CP-ENSO → NPGO/PDO → KE, hypothesis 3 20 ). …”

“…On the other hand, Anderson 19 has linked the decadal KE dynamics to a new mode of quasi-decadal variability, the Pacific Decadal Precession (PDP) 22 , 23 , which is characterized by a ~ 10 yr counterclockwise progression of a dipole structure of the North Pacific atmosphere (Hypothesis 2 in Fig. 1 b).…”

Enhanced Interactions of Kuroshio Extension With Tropical Pacific in a Changing Climate 

“…On the other hand, Anderson (2019) 20 has linked the decadal KE dynamics to a new mode of quasidecadal variability, the Paci c Decadal Precession (PDP) 21,22 , which is characterized by a ~10yr counterclockwise progression of a dipole structure of the North Paci c atmosphere (Hypothesis 2 in Figure 1b). This hypothesis asserts that the evolution of the PDP mirrors a quasi-decadal signal in KE.…”