Multidecadal Variability of Sea Surface Height and Volume Transport in the Northwestern Pacific Marginal Seas

Abstract

The driving mechanism for the multidecadal sea surface height (SSH) variability with a period of about 50‐year in the East Sea/Japan Sea and related dynamics in the northwestern Pacific marginal seas are investigated using a multi‐millennial pre‐industrial control climate model simulation. The model results suggest that multidecadal variability is associated with the meridional shift of zero‐wind stress curl in the central North Pacific. The SSH anomalies driven by open ocean wind stress curl anomalies propagate westward via baroclinic Rossby waves and drive an anomalous sea level setup around the Japanese Islands; this leads to variability in the Tsushima Warm Current (TWC) transport, with this linkage explicitly demonstrated using the island rule. Sea surface height anomalies propagating from the open ocean also affect the Kuroshio transport in the East China Sea by modulating the onshore side of the SSH across the Kuroshio. Although the changes in the transport of the Kuroshio and TWC have opposite responses to wind stress curl changes in the central North Pacific, their direct correlation is insignificant and weakly positive. With a multi‐millennial climate model simulation, this study allows a statistically robust finding on the mechanism for the multidecadal internal variability, complementing previous studies based on short term observation and reanalysis data.