Interannual Variability of Subsurface Intrusion of Low-Temperature and Salinity Shelf Water into the Kuroshio in the East China Sea

Interannual Variability of Subsurface Intrusion of Low- Temperature and Salinity Shelf Water into the Kuroshio in the East China Sea

Spatiotemporal characteristics of salinity and temperature on isopycnal surfaces and subsurface exchange of Kuroshio and ECS shelf water are investigated based on Simple Ocean Data Assimilation (SODA) reanalysis data from January 1958 to December 2008. Applying a neutral density variable γn and Empirical Orthogonal Function (EOF) analysis, dominant spatial features and corresponding temporal variability on both seasonal and interannual time scales are revealed on neutral surfaces 23.0-24.5 γn. The most remarkable characteristic of variability on interannual time scale is the anomalous strengthening of subsurface intrusion of less saline shelf water into the shelf edge and the Kuroshio region during strong La Niña years. Possible causes inducing the strengthening are found to be associated with extraordinarily large discharge of the Changjiang in the following years of strong El Niño as well as the variability of the Yellow Sea bottom cold water modulated by La Niña Events.