Surface Expression of the Kuroshio Extension Northern Recirculation Gyre

Abstract The Northern Recirculation Gyre (NRG) of the Kuroshio Extension (KE) has traditionally been viewed as subsurface‐intensified and difficult to identify at the sea surface. We combine a 2016–2025 subsurface mooring record, satellite altimetry, Argo trajectory‐based velocities, and historical near‐bottom velocities to reassess the sea‐surface expression of the NRG‐related westward flow and its relation to subsurface variability. At and near the mooring site, velocities show low‐frequency covariability across sampled depths and a westward time‐mean structure. In the altimetry‐defined surface‐expression region, westward surface flow becomes clearer and more frequent in the later record, while retaining strong interannual modulation. The clearer sea‐surface expression is accompanied by local eddy–mean adjustment in the adjacent KE–NRG shear band, as indicated by barotropic‐conversion and Reynolds‐stress diagnostics.