Driving mechanism of the Deep Antarctic Circumpolar Current by the meso-scale eddies..

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 14540407
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Kyoto University
• Principal Investigator: SAKAI Satoshi Kyoto University, Graduate School of Human and Environmental Studies, Associate Professor, 大学院・人間・環境学研究科, 助教授 (30144299)
• Co-Investigator(Kenkyū-buntansha): YAMADA Michio Kyoto University, Research Institute for Mathematical Sciences, Professor, 数理解析研究所, 教授 (90166736)
• Project Period (FY): 2002 – 2004
• Keywords: Rotating tank / Meso-scale Eddies / Antarctic Circumpolar Current / Deep water circulation

Research Abstract

It is known that the Antarctic Circumpolar Current is flowing the surroundings of Antarctica for the east to the depths considerably. Although this origin is vaguely considered to be what is depended on the wind which generally blows a sea top in many cases, it is hard to consider the mechanism which stress of a wind cannot affect the direct depths, and runs through density stratification through Ekman convergence and emission, and does that influence to the depths dynamically. Then, it is the purpose of this research to confirm whether an indoor experiment is conducted using a rotation tank, a turbulent flow isotropic as initial turbulence is given, and, finally the flow facing the east is formed in the surroundings of a pole of nonlinear acceleration of turbulence.
The experiment tank was making it rotate per minute 100 times with a cylinder form, changed depth of water in the shape of a concentric circle, and produced beta effect. Initial turbulence generating equipment repeated tria l and error many times, finally, is drawing out the stick inserted underwater in early stages, and carried out it to generating initial turbulence. Although this method considered another method at the beginning in order that the bunch of the drawn-out stick might interrupt the field of view of a camera, this method is turbulence's being generated most certainly and dividing the drawn-out stick by centrifugal force into two, and it is having developed the method of securing the field of view of a camera, and was made to adopt this method. Visualization of a flow hit the light of the shape of a sheet which put in order and made the light emitting diode to the styrene bead distributed underwater, and succeeded in visualizing the flow in the tank central part without the influence of the wind on surface tension or the water surface.
Although the initial turbulence of two or more sizes was given and being repeatedly experimented in the experiment, the quite strong flow facing the east was obtained altogether. Although it had resulted in becoming for the east when the probability which serves as west Nagare in the centering on pole concentric circle [this/in numerical computation]-like sea in comparison with the numerical computation of Yamada and others was high and the pole was shifted, in an experiment, it always becomes a flow facing the east. By numerical computation, boundary conditions are slip conditions and this is considered to be because for quantity of motion not to be given on the boundary in the concentric circle-like sea.