Cumulative Effect of Synoptic‐Scale Storms on Decadal Mixed‐Layer Temperature Variability in the Mid‐Latitude North Pacific

Abstract Decadal variability of mixed‐layer temperature ( T m ) in the mid‐latitude North Pacific plays a key role in air–sea interactions and regional climate. While previous studies have emphasized the role of large‐scale climate modes in this variability, the contribution of synoptic‐scale storms remains unclear. Using oceanic observations and the ERA5 reanalysis, we conduct a mixed‐layer heat budget analysis during storm‐active and storm‐weak periods within 1950–2020. Our results reveal that frequent storms contribute to a cumulative cooling of T m , primarily through anomalous meridional Ekman heat transport. During storm‐active periods, a stronger Aleutian Low coincides with increased storm activity and enhanced cumulative Ekman cooling, vice‐versa during storm‐weak periods. These findings highlight the importance of storm frequency in shaping decadal upper‐ocean variability and in improving decadal climate prediction skill with high‐resolution models.