Study of the "Vortex of Naruto" through multilevel remote sensing. Abstract Hydrodynamic characteristics of the "Vortex of Naruto" were investigated based on the remotely sensed data. Small scale vortices caused by the fast characteristics of the "Vortex of Naruto", that had not been done by the conventional field survey using boats. tidal currents at the Naruto Strait were surveyed through airplane remote sensing. Large scale vortices were surveyed through multi - level remote sensing using Landsat and airplanes. Under sea information was obtained through fluid mechanical by Takakazu MARUYASU, Sotoaki ONISHI and Tsukasa NISHIMURA c analysis aided by the hydraulic model tests. Small scale vortices were explained to be the coherent vortices in the free boundary layers between the tidal current and the dead water regions, and were revealed to cause the strong vertical water mixing at the strait. Large scale vortices were explained to be generated as the results of the amalgamation process of the small scale coherent vortices in 6 hours, and were revealed to cause the effective tidal exchange through the strait between Harima Sea and Kii Channel. Results obtained made it possible to catch the macroscopic view of the hydrodynamic Faculty of Science and Technology, Science University of Tokyo, Yamazaki, Noda-shi, Ciba, 278, Japan. 57
Fig. 1. Bottom topography of the Naruto Strait. Fig. 2. Relationship among the tidal current and the tidal levels under the spring tide condition; from the CHARTS No.6202. 58
Fig. 3. Flight course and shooting points of the synchronized photographing by a pair of airplanes. Flight altitude is 1,200 meter.
Fig. 4. Flight course and, shooting ptints of the photographing by a single airplane. Flight altitude is 1,200 meter. Fig. 5. Contour map of the sea surface.
Fig. 6. Principle of the Kameron-effect. Fig. 7. Vector map of the current velocity.
Fig. 8. Contour map of the velocity distribution. 63
Fig. 9. Flow regions composing the tidal current field. 64
Fig. 10. Schema of the coherent vortex model.
Fig. 12. Formation process of the small scale vortices and large scale onesat the Naruto Strait. Fig. 13. Water mass patterns in the different phase of the tidal current obtained from the Landsat imageries of (A), (B) and (C) of Plate 2 68
Fig. 14. Comparison of the loct of floats and the Landsat imageries of the large scale vortices. The loci were extracted from 69
Fig. 16. Effects of the shape of the vortex-pair on the tidal exchange.
Fig. 17. Eqziprent and procedure of the experiment.
Fig. 18. Successive pictures of the front of the upwelling flow caused by the vortex. The time lag is a second. Fig. 19. Upwelling volume flux as a function of the vortex strength. Fig. 20. Equipment and procedure of the experiment.
Fig. 21. Tidal exchange process reproduced in the hydraulic model of the Naruto Strait.
2) Taylor,G. I.: Statistical theory of turbulence, Proc. of London, Series A, Vol. 151,pp. 421 `464 (1935) 3) Winnant, C. D. and Browand, F. K.: Vortex -Pairing, the mechanism of turbulent mixing lager growth at moderate Reynolds number, J. Fluid Mech. Vol.63, Part2, pp.237 `255 (1974)
Photo. 1. 2. Airphoto of the Naruto Strait (flight height of 1,000m)
Photo 2. 4. Landsat MSS imageries tidal phases of digitally Puff at enhanced diffrent