Eddies advected by time-dependent Sverdrup circulation in the western boundary of the subarctic North Pacific

It has been reported that several eddies frequently exist along the Kuril-Kamchatka Trench (K-K Trench, hereafter), the western boundary of the subarctic North Pacific. Lagged correlation maps of the altimeter-derived sea level anomalies (SLAs) along the trench indicate that the southern eddies on the whole move northeastward along the K-K Trench and the northern eddies, on the other hand, move southwestward. By tracking each anticyclonic eddy, its propagating velocity along the trench is calculated. The time series of the tracked 7 eddies shows similar seasonal variation to those of the first empirical orthogonal function (EOF) of the SLA maps and to those of the Sverdrup transport at 40°N. In addition, when more than two eddies remotely exist in the studied area, they show coherent moving patterns. These results suggest that the eddies in the western boundary region of the subarctic North Pacific are advected by the time-dependent wind-driven current.