Axis, velocity and volume transport of the Kuroshio in the Tokara Strait

对黑潮的流量和热量输送进行监测是了解北太平洋气候系统的必要手段。托卡拉海峡是监测运输情况的便利海域。许多具有不同时间和空间尺度的现象导致了从海平面坡度的波动估计的运量的波动。例如，黑潮锋在海峡中的迁移将对波动做出贡献。因此，我们利用卫星红外图像、海平面记录和海温时间序列描述了锋面迁移与输送起伏、锋面垂直结构和锋面迁移发生的关系。通过分析，我们得到了以下结果。1.从海面延伸到约200m深的锋面向北迁移，伴随着中岛与佐佐木之间体积输送的增加，锋面起源于屋久岛以西的陆架水舌。2.向北迁移约4天后，流入鹿儿岛湾的海流和大美支流增强，虽然在中野岛和八岛之间普遍存在锋面，但黑潮的主要流量输送应该存在于中野岛以南。这意味着黑潮的轴线将存在于该岛以南。因此，我们通过对BT和GEK资料的分析，确定了中野岛以南一个水深为750m的城市的平均轴线位置，并测量了该城市的地下流速。通过分析和测量，我们得到了以下结果。3.在200米深处，地轴的典型温度为17.2ﾟC。该轴的平均位置在中野岛附近。该位置的标准差为*25公里。4.500米处的流速大于300m处的流速，且大致平行于等深线。

It is necessary for understanding North Pacific climate system to monitor volume and heat transports of the Kuroshio. The Tokara Strait is a convenient sea area for monitoring of the transports. Many phenomena which have different time and space scales contribute fluctuation of the volume transport estimated from fluctuation of a sea level slope. For an example, migration of the Kuroshio front in the strait will contribute the fluctuation. So, we described relations between the front migration and the transport fluctuation, vertical structure of the front and generation of the front migration, using satellite infrared image, sea level records and time series of sea surface temperature. From the analyses, we got following results. 1. Northward migration of the front which extends from the sea surface to about 200m deep and originates from tongues of the shelf water west of the Yakushima is accompanied by increase of the volume transport between the Nakanoshima and the Satamisaki. 2. The inflow into the Kagoshima bay and the Ohsumi Branch Current strengthen after about 4 days of the northward migration.Although the front has been generally found between the Nakanoshima and the Yakushima, a major part of the volume transport of the Kuroshio is supposed to exist south of the Nakanoshima. This means that the axis of the Kuroshio will exist south of the island. So, we determined average position of the axis analyzing data of BT and GEK and measured subsurface velocity at a cite south of the Nakanoshima where the water depth is 750m. From the analysis and the measurement, we got following results. 3. A typical temperature showing the axis is 17.2ﾟC at 200m depth. The averaged position of the axis is near the Nakanoshima. The standard deviation of the position is *25km. 4. Velocity at 500 depth is higher than that at 300m deep and approximately parallel to isobaths.