Study on the Kyucho in the Bungo Channel

对丰后海峡的Kyucho进行了调查。通过长期的水温监测、CDT调查等野外观测和历史资料分析，研究了其结构、产生周期、产生机制及其对海洋环境的影响。获得了以下结果。(1)丰后海峡中的Kyucho是来自太平洋的温暖，较轻的水团侵入的现象，基本上是重力流。温暖的水团侵入海峡的东半部，向右侧看海岸。(2)小潮前后会出现Kyucho。(3)Kyucho主要出现在夏季。(4)Kyucho的产生取决于垂直混合强度的变化。但是，对垂直混合的定量研究表明，除了这种效应之外，还必须有其他一些机制。(5)Kyucho的强度受海洋扰动的影响。当小潮时，从海洋向丰后海峡南部供应的暖水团福尔斯时，Kyucho会加强。(6)Kyucho对丰后海峡东海岸沿着的海洋养殖产生了许多影响，例如由于水温的突然变化而导致养殖鱼类的疾病或死亡。另一方面，九曲湾对维持水质的海湾水的更新做出了贡献，并支持大规模养殖。今后有必要对包括地球自转影响在内的生成机制进行研究。

Investigations were made on the Kyucho in the Bungo Channel. Its structure, periodicity of its generation, mechanism of its generation and its influences on the marine environment were studied by the field observations, such as long term monitoring of water temperature and CDT surveys, and analyses of the historical data. The following results were obtained.(1) The Kyucho in the Bungo Channel is a phenomenon of the intrusion of a warm, lighter water mass from the Pacific Ocean, and is fundamentally a gravity current. The warm water mass intrudes into eastern half of the channel looking the coast to its right side. (2) The Kyucho appears around neap tide. (3) The Kyucho appears mainly around summer. (4) Generation of the Kyucho is determined by the variation of the intensity of vertical mixing. But quantitative examination of the vertical mixing suggested that some other mechanism must work in addition to this effect. (5) The intensities of the Kyucho is influenced by the oceanic disturbances. The Kyucho is intensified when the supply of warm water mass from the ocean to the southern part of the Bungo Channel falls on neap tide. (6) The Kyucho gives many influences on the marine cultures along the eastern coast of the Bungo Channel such as disease or decease of the cultured fish due to the sudden change of water temperature. On the other hand, the Kyucho contributes to the renewal of the bay water maintaining water quality, and supports the large scale cultures.Study on the generation mechanism including the effect of earth's rotation is necessary in future.