Potential predictability of interannual variability in the Kuroshio extension jet speed in an eddy-resolving OGCM

Variability in the Kuroshio Extension (KE) jet speed has been considered to impact the upper-ocean ecosystem. This study investigates potential predictability of interannual variability in the KE jet speed that could arise from the propagation time of wind-driven Rossby waves as suggested by previous studies, through prediction experiments with an eddy-resolving ocean general circulation model (OGCM) under the perfectmodel assumption. Despite the small number of experiments available because of limited computational resources, the prediction experiments with no anomalous atmospheric forcing suggest some predictability for not only broad-scale sea surface height anomalies (SSHAs) but also the frontal-scale KE jet speed. The predictability is confirmed in a 60-yr hindcast OGCM integration as a significantly high correlation (r = 0.68) of 13-month running mean time series of the anomalous KE jet speed with SSHAs that appear in the central North Pacific Ocean 3 yr earlier. Although with fewer degrees of freedom, the same lag relationship can be found between satellite-measured SSHAs and the geostrophically derived KE jet speed.