Results 6, Mushroom Structure, 3D Close-Up & Animation

Figure 7 shows the close-up view of the three dimensional vorticity and velocity fields for the structure shown in Fig. 6. The wider anticyclonic (blue) vortex above is accompanied by the narrower cyclonic (red) vortex surface below, and upward currents connect the vortex pair. Hereafter, we refer such a structure to as a mushroom structure, since the anticyclonic and cyclonic vortexes resemble a cap and stem of a mushroom, respectively.

The thickness of the mushroom cap is roughly 200 m, and is likely to be determined by the internal dynamics of the model. In order to confirm the thickness is insensitive to the model mixed layer depth (also 200 m in the standard case), we conducted an experiment with the 100 m mixed layer depth, with the half vertical grid size (25 m). Even in this case, the shape of the mushrooms is essentially the same as the standard case.

As noted earlier, one of the interesting character of the mushroom structure is its temporal development. Figure 8 shows the animation of the mushroom structure. The stem of the mushroom began developing around 130 hours from the bottom. Simultaneously the cap started emerging from the top-right hand side of the stem, and rapidly encircled the stem below. The pair of the cap and stem took its mature shape around 133-135 hours. Then the mushroom structure was weakened till 147 hours, and was again strengthened after that. Near the end of the visualization period (around 170 hours), the upper anticyclonic vortex is no longer circular, probably due to advective influence of vortexes in adjacent regions, such as a tube-like cyclonic vortex extending in the x-direction around y=3.6 km in the upper layer.

Figure 7. Three dimensional close-up view of vorticity (blue and red colored surface) and velocity (green cones) fields for a mushroom-structure. As in Fig. 6, the surfaces of an amplitude of 2.5*10^-4s^-1 for the three-dimensional vorticity are visualized, and red (blue) color indicates that the vertical component of the vorticity is positive (negative). The maximal three-dimensional velocity in the visualized domain is 0.067 ms^-1.

Figure 8. Same as Fig. 7, but for the animation from 121 to 174 hours. In order to restart the animation, please press reload bottom of your browser. Similar animation for the heton is shown in Fig. A3.