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.

Skillful Multiyear Prediction of the Kuroshio and Gulf Stream Jets and Eddy Activity

“…While findings from these studies have provided important insights into the potential predictability of WBCs, forecast skill for spatiotemporal variations in frontal‐scale oceanic features in the WBC regions has not been rigorously assessed in an operational sense. Several recent studies have demonstrated operational dynamical forecasting systems that can make skillful muti‐year predictions of large‐scale features of the Kuroshio Extension (KE) (Joh et al., 2022; Kim et al., 2023; Siqueira et al., 2021). However, the horizontal resolutions of ocean models and/or initial conditions adopted in these studies may not be sufficient to explicitly resolve the frontal structure of WBC jets and vigorous mesoscale eddies.…”