The Kuroshio plays a crucial role in regulating the thermal structure in the area south of Japan, and its variability significantly influences subsurface temperature distribution. Based on more than 30 years reanalysis data (JCOPE2M), this study investigates the interannual variability of subsurface temperature south of Japan using empirical orthogonal function (EOF) analysis. The EOF results show that the variability of subsurface temperature is primarily dominated by the first two modes, which together explain more than 60% of the total variance. The first mode is closely associated with the Kuroshio large meander, reflecting large-scale adjustments of the Kuroshio path. The second mode exhibits an approximately 4-year periodic oscillation and represents the coupled variability between the Kuroshio path and mesoscale eddy activity, characterized by the development of cyclonic cold eddies under offshore path conditions and the weakening of eddy activity under nearshore path conditions. Overall, the interannual variability of subsurface temperature south of Japan exhibits a clear hierarchical structure, characterized by the combined effects of large-scale path variability and mesoscale dynamical processes.
 

Kuroshio,EOF,Subsurface Temperature,South of Japan