An Atlantic-driven rapid circulation change in the North Pacific Ocean during the late 1990s

Chau-Ron Wu,Noel Keenlyside,You-Lin Wang,Yong-Fu Lin,Jin-Yi Yu

doi:10.1038/s41598-019-51076-1

Abstract

Interbasin interactions have been increasingly emphasized in recent years due to their roles in shaping climate trends and the global warming hiatus in the northern hemisphere. The profound influence from the North Atlantic on the Tropical Pacific has been a primary focus. In this study, we conducted observational analyses and numerical modeling experiments to show that the North Atlantic has also strongly influenced the Extratropical North Pacific. A rapid and synchronous change in the atmospheric and oceanic circulations was observed in the North Pacific during the late 1990s. The change was driven by the transbasin influence from the Atlantic Ocean. During the positive phase of the Atlantic Multidecadal Oscillation (AMO) since the 1990s, the anomalously warm North Atlantic triggers a series of zonally symmetric and asymmetric transbasin teleconnections involving the Inter-tropical Convergence Zone (ITCZ), Walker and Hadley circulations, and Rossby wave propagation that lead to a decrease in wind stress curls over the Pacific subtropics, resulting in an abrupt weakening in the North Pacific subtropical gyre (NPSG) and the Kuroshio Current.

Highlights

Many lines of evidence demonstrate that the climate system has been warming since the last century
Analyses of sea-surface temperature anomalies (SSTAs) and sea-surface height anomalies (SSHAs) averaged over the western North Pacific further support a drastic alteration in ocean properties around 1998–99 (Fig. 1f,g)
A weakening of surface westerlies is evident over the North Pacific during the 1999–2013 period in this multi-analysis mean as well as in each individual reanalysis (Fig. S2)

Summary

Materials and Methods

The monthly-mean SSTs of the ERSST (Extended Reconstructed Sea. Surface Temperature, version 5) were provided by the NCEI/NOAA (National Centers for Environmental Information/National Oceanic and Atmospheric Administration, https://data.nodc.noaa.gov) with 2° × 2° horizontal resolution since 185438. The daily Advanced Very High Resolution Radiometer – Optimum Interpolation SST (AVHRR-OISST, http://www.ncdc.noaa.gov/oisst) data on a global 0.25° grid were used for Fig. 5. The daily absolute geostrophic velocity (GSV) products (version: DT-MADT two-sat) were produced by Ssalto/Duacs and distributed by the AVISO (Archiving, Validation and Interpretation of Satellite Oceanographic Data, http:// www.aviso.altimetry.fr) on a global 0.25° grid since 1993. Model experiments were carried out with prescribed AMO-associated SSTs in the North Atlantic (NA) (0°–70°N). More analyses and discussion on the statistical significance have been included in Supplementary Information

Author Contributions

Findings

Additional Information