Behavior of oceanic currents in shelf regions

对马流、黄豆流和津加流在浅海陆架区域流动。这些洋流的性质与公海上的洋流有很大的不同，因为它们的洋流在海底保持着相当大的强度，并且它们在海底受到很大的摩擦。对陆架地区洋流的了解非常有限，尽管最近对它的需求有所增加。通过水槽试验、数值模拟和数据分析，研究了陆架区域洋流的基本性质。考察了水流结构对海岸线与入流相对夹角的依赖性。我们成功地再现了流入方向向右并与海岸线平行时沿海岸呈窄带状的黄豆流，以及流入方向与海岸呈矩形时沿海峡口呈大涡流的津加流。最有趣的特征是当流入流向左边时。在海峡口前方产生椭圆涡旋，涡旋呈顺时针旋转。涡流非常不稳定，在相当早的阶段就破裂了。研究了椭圆涡旋的详细性质。这种复杂的涡旋运动的行为似乎可以解释津加流和对马流的变化特征。建立了适用于局部海底地形的两层数值模型。虽然该模型在现阶段仅对特定现象进行了应用，但该模型对陆架区域的电流分析是有效的。数据分析是根据海岸站和定期班轮上的潮汐和温度记录进行的。结果表明，这些可用于监测大陆架区域的洋流。

The Tsushima Current, the Soya Current and the Tsugaru Current flow in shallow shelf regions. The nature of these current is quite different from currents flowing open ocean, as their current keeps its considerable magnitude down to bottom and they receive significant friction form bottom. Knowledge of the currents in shelf regions is very limited though demands for it has been increased recently. Basic nature of the currents in shelf regions was studied through tank experiment, numerical modelling and data analysis. Dependence of current structure on the relative angle between coast line and inflow are examined. We succeeded to reproduce the current having shape of narrow band along the coast like the Soya Current when the inflow is directed to right and parallel to coast line, and the current with large eddy off the strait mouth like the Tsugaru Current when inflow direction is rectangular to the coast. Most interesting feature is observed when the inflow is directed towards left. The elliptic eddy is produced on front of strait mouth and the eddy rotates clockwise. The eddy is very unstable and breaks down in rather early stage. The detailed nature of the elliptic eddy was examined. The behavior of this complicated eddy motion seems to give some explanations of changeable feature of the Tsugaru Current and the Tsushima Current. We developed numerical two layer model which is applicable for local oceans with bottom topography. Though the application of the model has made only for specified phenomena in the present stage, the model was showed effective for the analysis of currents in shelf region. The data analysis was made for tidal records and temperature records taken on coastal stations and on board of regular liners. Results indicate that these can be used for monitoring oceanic currents in shelf regions.