Exceptional multi-year prediction skill of the Kuroshio Extension in a high-resolution decadal prediction system

Abstract The Kuroshio Extension (KE) has far-reaching influences on climate as well as on local marine ecosystems. Thus, skillful multi-year to decadal prediction of the KE state and understanding sources of skill are both societally important and scientifically challenging. Retrospective forecasts using a high-resolution coupled system at an eddy-rich (0.1°) ocean and 0.25° atmosphere horizontal resolution show exceptional skill in predicting decadal KE variability up to lead year 4, substantially higher than the skill found in a similarly configured low-resolution (~1° for all components) system. The exceptional skill is attained because the high-resolution prediction system can more realistically simulate the westward propagation of initialized SSH anomalies in the central North Pacific and their expression within the sharp KE front. These results argue for the use of high-resolution models for future studies that aim to predict changes in the western boundary current systems and associated biological fields.