Abstract: Vortex shedding downstream of Green Island due to passing of the Kuroshio is numerically studied. The numerical model is based on depth-averaged shallow-water equations with the space-time least-squares finite-element method. Vortex characteristics, such as spatial scales (aspect ratio and dimensionless width), temporal scale (Strouhal number), and propagation speed of the vortices are quantified. It is found that aspect ratio = 2.4, dimensionless width = 1.1, and Strouhal number = 0.157 for Reynolds number 100. The computed spatial scales and temporal scale agree reasonably with available satellite images and in situ measurements, as well as other simulation results. The magnitude of the propagation speed of the vortices is found to be of the same order as that of the Kuroshio, implying that the nonlinearity of vortices as well as the interactions between vortices and the Kuroshio are strong.