Effects of Kuroshio intrusion optimization on the simulation of mesoscale eddies in the northern South China Sea

The impacts of Kuroshio intrusion (KI) optimization on the simulation of meso-scale eddies (MEs) in the northern South China Sea (SCS) were investigated based on an eddy-resolving ocean general circulation model by comparing two numerical experiments with differences in their form and intensity of KI due to the optimizing topography at Luzon Strait (LS). We found that a reduced KI reduces ME activities in the northern SCS, which is similar to the observations. In this case, the biases of the model related to simulating the eddy kinetic energy (EKE) west of the LS and along the northern slope are remarkably attenuated. The reduced EKE modeling bias is associated with both the reduced number of anti-cyclonic eddies (AEs) and the reduced amplitude of cyclonic eddies (CEs). The EKE budget analysis further suggests that the optimization of the KI will change the EKE by changing the horizontal velocity shear and the slope of the thermocline, which are related to barotropic and baroclinic instabilities, respectively. The former plays the key role in regulating the EKE in the northern SCS due to the changing of the KI. The EKE advection caused by the KI is also important for the EKE budget to the west of the LS.