| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1994: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
The bimodal path dynamics of the Kuroshio and their transformation process have been examined in the course of this study. In the first year, a flat bottom model with realistic coastal topographies south of Japan was assumed and the coastal topographic effect was examined. It has been pointed out that the transformation from straight path to large meander path is due to the positive vorticity supply from the Cape Muroto and Kii Penisula. Conversely, the transformation from the large meander path to the straight path is caused by no supply of the positive vorticity by the separated current path from the coastal topographies. In this second year, bottom topographies south of Japan is further included in the numerical model and their effects are examined. It is shown that the large meander path commonly separates from the Cape Muroto. If only the coastal topography of Kii Peninsula is excluded from the model, separation of the mean flow is carried out at the Cape Muroto. However, the sepa
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ration point shifts to east of the Cape Muroto, if the coastal topography of the Cape Muroto is excluded. If the coastal topographies of the Cape Muroto and Kii Peninsula are excluded, the separation point shifts further downstream. It is demonstrated that topographic effect of the Cape Muroto has an important influence on the bimodal path dynamics of the Kuroshio. Because of the stabilization effect of the bottom slope, large meander path is formed only in the case with large in- and outflow of 80 Sv and small eddy viscosity. It is suggested that the large meander path is formed through the baroclinic instability under the condition of strong nonlinear system. The two papers describing these results were accepted to La mer and they are now in printing. These results give important views for a future study on the Kuroshio. However, corresponding study on the observational data analyzes are still lacking. Then, I performed three sectional observations across the Kuroshio and I am now examining results of the observation. The topographic effect of Cape Muroto will be dicussed by use of the historical observational data. Less
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