Fig. 1

Topography of the northern South China Sea, where black solid lines, thick dotted lines and fine dotted lines represent 300, 1000 and 3000 m, respectively. The magenta dashed line shows the boundary of warm eddy during its lifetime, and the red line is its trajectory simulated by the model, where green triangle, star and circle represent the generation site, the time when the tracers were released and the decay site of the eddy, respectively. Similarly, the blue solid line shows the trajectory of the warm eddy during its lifetime from the AVISO data, where blue triangle and circle are the generation and decay sites of the eddy, respectively"

Fig. 2

A total of 10000 tracer particles were released at 10 m on the 57th day of the eddy lifespan. The figures show the changes in spatial distribution of the tracers with time. The red dots represent locations of the tracers, and the magenta line is eddy trajectory. Black arrows show the current field. To see the flow field inside this anticyclone clearly, we randomly selected 1000 particles for making this figure"

Fig. 3

Time series showing the variation of the number of tracers inside the eddy. Black solid line, black dashed line and gray dashed line represent the tracers released at 10, 50 and 100 m, respectively"

Fig. 4

Time series showing (a) radius, (b) vorticity, (c) eddy kinetic energy, (d) potential vorticity, (e) nonlinearity, (f) shearing deformation rate, stretching deformation rate of the warm eddy after releasing the tracers. The orange line is the time series of tracer number. All of the variations are normalized by their maximum values respectively"

Fig. 5

Spatial distribution of warm eddy physical properties in decay stage. (a) EKE, (b) vorticity, (c) divergence, and (d) deformation. There exists high EKE around the edge of the warm eddy. Positive and negative vorticity appear alternatively at the periphery of the eddy. Strong divergence accompanied by convergence is observed southwest of the eddy. The deformation is the strongest at the edge of the eddy. The eddy center is marked with “×”"

Fig. 6

3D trajectories of 40 tracers, which were selected randomly. The tracers were released on December 03, 2003. During most of their lifetimes, they experienced spiraling downward vertical motion, and travelled southwestward. The cyan dotted lines represent negative vertical velocity and magenta lines are positive vertical velocity. Green stars and triangles are generation and termination locations of the tracers. The red line and dot are eddy shape and center, respectively. The anticyclone has good transportation capability"

Fig. 7

Mean depths of the tracers released at 10 m (red), 50 m (blue) and 100 m (magenta), respectively. The gray parts are the corresponding standard deviation."

Fig. 8

3-D variation of tracers and potential vorticity spatial distribution with time. Shading represents potential vorticity, and magenta dots are tracers’ locations"