To better understand the behavior of water mass beneath the Tsushima Warm Current (TWC), we use the vertical cross-sections of potential temperature, salinity and dissolved oxygen in the Japan Sea obtained by the T/V Oshoro Maru of the Hokkaido University during 8–29 June in 2011 to analyze its origins and variations. The results show that the potential temperature and salinity beneath the TWC varies little, but the dissolved oxygen varies largely with the geographical location. There are two deep water masses with different dissolved oxygen content below the TWC. One is on the coastal side with the low dissolved oxygen, and the other is on the offshore side with the high dissolved oxygen. It is inferred that the former one is relatively old water and the latter is the new water. By using the phosphate (PO4) and the apparent oxygen utilization (AOU) relationship, we calculate the PO40 (preformed PO4) as a water mass tracer. These results suggest that the water masses beneath the TWC with high and low dissolved oxygen originate from the same surface water mass in the central Japan Sea.

中文翻译：

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日本海对马暖流下水团的行为

为了更好地了解对马暖流 (TWC) 下水团的行为，我们使用了北海道大学的 T/V Oshoro Maru 在 8 年期间获得的日本海潜在温度、盐度和溶解氧的垂直截面。 – 2011 年 6 月 29 日分析其起源和变化。结果表明，TWC下方的潜在温度和盐度变化不大，但溶解氧随地理位置变化很大。TWC下方有两个溶解氧含量不同的深水团。一个是在沿海一侧，溶解氧含量低，另一个在离岸一侧，溶解氧含量高。推断前者是比较老的水，后者是新水。通过使用磷酸盐 (PO4) 和表观氧利用率 (AOU) 的关系，我们计算出 PO40（预制 PO4）作为水质量示踪剂。这些结果表明，具有高和低溶解氧的 TWC 下方的水团来自日本海中部的同一地表水团。