| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1988: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1987: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Benten-ike has about 6 m depth and the 1st thermocline only. The internal wave has some modes, and their wave velocities are 2-10 cm/sec. For these values two layers interfacial wave model was suitable. For the 2nd thermocline Holmboe model which used the steepest temperature gradient was suitable, and was calculated to have a velocity of 40 cm/sec. There were periods of 28min., 7 hours, and 15 hours. Calculated values by Holmboe model were also near values to them. As the results of observations which measured water temperature fluctuations at 7 depths at a interval of 1 m on the 2nd thermocline, the existence of a modal structure was estimated. The travelling height of water particle on the 2nd thermocline was usually less than 1 m. Therefore, also with the long period , mixing by internal wave under ordinally hydrological and meteorological conditions will not be able to be expected. Also, mixing breaking through the 1st thermocline is very difficult. By the data of convectional mixing on autumn, a falling velocity of a mass of cold water produced by surface cooling were obtained. It was found that theoretical results were well fitted to those data. Hereafter, the authors' research subject is to find out the relation between the lowering of lower limit of this concectional flow and the air and water temperature.
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