Division rate of the volume transport between the Tsugaru Warm Current and the northward Tsushima Current

为了了解日本海环流的物理性质以及对马海流在津轻暖流和北上对马海流之间的输送分配率，进行了数值研究、考察航行和资料分析。数值研究发现，日本海的环流具有明显的季节变化，冬季以风驱动环流为主，夏季以三个海峡的进出流激发环流为主。通过ADCP观测津轻暖流的输送，发现津轻暖流的输送具有明显的日变化，这是由于下游方向沿着海平面差或气压梯度引起的。发现1.3 Sv的平均输送量与另一个1.4 Sv的值非常一致，该值是根据青森县以西和北海道南部CTD断面的地转体积输送沿着平衡估算的。结合海平面观测资料分析发现，津轻暖流和向北气流的输送与海平面的变化成正比，海平面下降的差异。由此得出结论，两股海流之间的输送分配率取决于沿着津轻海峡与沿着青森县西海岸和北海道南部的海平面差之比。

Numerical study, research cruise and data analysis have been made in order to understand the physics of the circulation in the Japan Sea and the division rate of the transport of the Tsushima Current between the Tsugaru Warm Current and the northward Tsushima Current. It is found by the numerical study that the circulation in the Japan Sea has a clear seasonal cycle : the wind-driven circulation is dominant in winter whereas the circulation excited by the in- and outflow through the three straits is dominant in summer. It is suggested that the depth of the current relative to the bottom west of Aomori Prefecture might be responsible for the division rate of the transport.Observations of the transport of the Tsugaru Warm Current by ADCP show a very distinct diurnal variation, which is shown to be caused by the sea level difference or pressure gradient along the down stream direction. The mean transport of 1.3 Sv is found to be in good agreement with another value of 1.4 Sv estimated from the balance of geostrophic volume transports along the CTD sections west off Aomori Prefecture and southern Hokkaido.Transport estimations by Ohtani et al. (1989)are analyzed together with sea level observations to find that the transports of the Tsugaru Warm Current and the northward flow aie in proportion to the downward sea level differences. This leads to a conclusion that division rate of the transport between the two currents is determined by the ratio of the sea level difference along the Tsugaru Strait to that along the western coast of Aomori Prefecture and southern Hokkaido.