Mid and Deep Circulation in the Japan Sea

日本海是一个小型海洋，是海洋数值预报的一个很好的试验海盆。然而，到目前为止，中深循环还没有得到很好的理解。在两个财政年度内，我们进行了4次巡航调查表层以下的环流（1994，1995）作为日本、韩国和俄罗斯的国际合作野外研究，在日本海主要部分进行了夏季航次的CTD和化学测量（1994，7.5 -7.25）的结果表明，在10年内，深层温度以0.02 ℃/10年的速率上升，而氧气则呈下降趋势，说明至少在最近10年内没有深层水的形成。通过分析恢复的长期（1993.8-1994.8）海流系泊资料，在日本海盆深部探测到了月尺度、流速超过20 cm/s的强中尺度活动。19961996.2.15-2.25年冬季在海参崴附近海域进行的第二次冬季考察（www.example.com）探测到了600 m深的深对流，而第一次冬季考察（www.example.com）没有发现深对流的迹象1995.3.1-3.15。由于1995年冬季温暖，夏季在若狭湾外进行了ADCP和CTD测量（1995.5.26-6.8）观测到对马海流近岸分支以下的次表层逆流，其速度超过10 cm/s。这一暗流的存在和结构与几个数值模式的结果有很好的一致性，在中深层环流研究中发现了许多新的方面，对今后的日本海环流研究有重要意义。

The Japan Sea is a mini ocean and a very good test basin for the numerical ocean prediction. However, so far, the intermediate and deep circulation haven't been well understood. We carried out 4 cruises to survey the circulation below the surface layr during two fiscal years (1994,1995) as international cooperative field researches between Japan, Korea nad Russia.The CTD and chemistry measurements during the summer cruise in the main part of the Japan Sea (1994,7.5-7.25) showed the increase of the temperature in the deep layr with the rate of 0.02 C per 10 years and the oxgen decrease, suggesting no formation of the deep water during at least last ten years. Strong mesoscale activities with the time scale of month and the velocity exceeding 20 cm/s were detected in the deep Japan Basin by analyzing the recovered long-term (1993.8-1994.8) current mooring data. Many informations about the distribution of the salinity minimum layr with the oxgen maximum were obtained in this cruise.The second winter cruise (1996.2.15-2.25) carried out off Vladivostok in '96 winter detected the deep convection reaching 600m depth, while no sign of deep convection could be found in the first winter cruise (1995.3.1-3.15), because the winter in 1995 was warm.The ADCP and CTD measurements carried out during the summer cruise off the wakasa bay (1995.5.26-6.8) observed the subsurface counter current below the nearshore branch of the Tsushima current over the continental shelf break with the speed exceeding 10 cm/s. The presence and the structure of this undercurrent correspond well to the results of several numerical models.Many new aspects about the intermediate and deep clrculation found in this research will contribute much to the future studies for the Japan Sea circulation.