Branching of the Tsushima current in the Japan Sea
- 313 Downloads
Although the Tsushima Current exhibits a complicated meander in the interior region of the Japan Sea, its path is more regular in the southwest region near the Tsushima Strait, and three branches have often been recognized there by many investigators. However, the detailed structures and temporal variabilities of these branches have not been clarified, and so they are studied here by analysing temperature, salinity and sea level data.
It is shown that the existence of the first branch (the nearshore branch along the Japanese coast) can be detected from salinity distributions at least during the period from March to August. The third branch (the Eastern Korean Current) exists in all seasons. On the other hand, the second branch (the offshore branch) is seasonally variable and can be identified only in summer from June to August.
Along the Japanese coast of southwest Japan Sea, the main pycnocline intersects the gentle slope on the shelf at a depth between 150 and 200 m. The first branch is found on the coastal side of the line where the main pycnocline intersects the bottom slope. On the other hand, the second branch is formed just on the seaward side of this line.
Sea level differences in the Tsushima Strait, i.e., between Hakata and Izuhara and between Izuhara and Pusan, show that the seasonal variation of the surface velocity (or volume transport) is small in the eastern channel and large in the western channel. The period during which the surface velocity and volume transport in the western channel increase corresponds well to the period during which the second branch exists.
These results suggest that the effects of bottom topography and oceanic stratification in the Japan Sea as well as the time variation of inflow through the western channel of the Tsushima Strait play important roles in the formation of the second branch.
KeywordsSurface Velocity Bottom Topography Volume Transport Bottom Slope Salinity Distribution
Unable to display preview. Download preview PDF.
- Central Meteorological Office of the Republic of Korea (1966–1976): Monthly weather report. Daily meteorological data for the standard meteorological stations (1966–1976).Google Scholar
- Fisheries Research and Development Agency of the Republic of Korea (1974): Annual report of oceanographic observations,22. Sectional oceanographic data (1973).Google Scholar
- Fisheries Agency, Japan (1972–1980): The results of Fisheries Oceanographical Observation. Hydrographical and BT observations (1969–1976).Google Scholar
- Hydrographic Office of the Republic of Korea (1967–1977): Technical reports. Results of tidal observation (1966–1976).Google Scholar
- Japan Maritime Safety Agency (1968–1978): Data report of hydrographic observations—Series of Tide (1966–1976), Nos. 4–13.Google Scholar
- Japan Meteorological Agency (1966–1977): Monthly report of the Japan Meteorological Agency. Meteorological observations for Jan., 1966 to Dec, 1976.Google Scholar
- Japan Meteorological Agency (1973–1978): The results of marine meteorological and oceanographical observations (Jan. to June, 1972–July to Dec, 1976), Nos. 51–60.Google Scholar
- Kajiura, K., M. Tsuchiya andK. Hidaka (1958): The analysis of oceanographical condition in the Japan Sea. Rep. Develop. Fisher. Resour. in the Tsushima Warm Current,1, 158–170. (in Japanese).Google Scholar
- Kawabe, M. (MS): Branching of the Tsushima Current in the Japan Sea, Part II. Numerical experiment. (submitted to J. Oceanogr. Soc. Japan).Google Scholar
- Kawai, H. (1974): Transition of current images in the Japan Sea.In, The Tsushima Warm Current—Ocean structures and fishery, ed. by Fishery Soc. Japan, Kôseisha-kôseikaku, pp. 7–26 (in Japanese).Google Scholar
- Miida, T. (1976): Current characteristics measured with current meters at fixed stations. Bull. Japan Soc Fish. Oceanogr., (28), 33–58 (in Japanese).Google Scholar
- Moriyasu, S. (1972a): The Tsushima Current.In, Kuroshio—Its physical aspects. ed. byH. Stommel andK. Yoshida, Univ. Tokyo Press, Tokyo, pp. 353–369.Google Scholar
- Moriyasu, S. (1972b): Hydrography of the Japan Sea. Marine Sciences (Kaiyô Kagaku),4, 171–177 (in Japanese with English abstract).Google Scholar
- Naganuma, K. (1973): On the discussions on the existence of the third branch of the Tsushima Current. News letter of Japan Sea Regional Fisher. Res. Lab., (266), 1–3 (in Japanese).Google Scholar
- Naganuma, K. (1977): The oceanographic fluctuations in the Japan Sea. Marine Sciences (Kaiyô Kagaku),9, 137–141 (in Japanese with English abstract).Google Scholar
- Ogawa, Y. (1974): The relation between the high saline water in the Japan Sea and Tsushima Current. Bull. Japan Soc. Fish. Oceanogr., (24), 1–12 (in Japanese).Google Scholar
- Ohwada, M. and K.Tanioka (1971): Currents and distributions of water masses in the Japan Sea. Rep. Study on the Japan Sea: Special budget for research in fiscal year 1969, Science and Technology Agency (Shôwa 44 nendo tokuchô-hi, Nipponkai ni kansuru sôgôkenkyû hôkokusho), 51–72 (in Japanese).Google Scholar
- Shimomura, T. andK. Miyata (1957): The oceanographical conditions of the Japan Sea and its water systems, laying stress on the summer of 1955. Bull. Japan Sea Regional Fisher. Res. Lab., (6), 23–97 (in Japanese with English abstract).Google Scholar
- Suda, K. andK. Hidaka (1932): The results of the oceanographical observations on board R.M.S. ‘Syunpû Maru’ in the southern part of the Japan Sea in the summer of 1929, Part 1. J. Oceanogr. Imp. Mar. Observ.,3, 291–375 (in Japanese).Google Scholar
- Suda, K., K. Hidaka, Y. Matsudaira, E. Kurashige, H. Kawasaki, andT. Kubo (1932): The results of the oceanographical observations on board R.M.S. ‘Syunpû Maru’ in the southern part of the Japan Sea in the summer of 1930. J. Oceanogr. Imp. Mar. Observ.,4, 1–174 (in Japanese).Google Scholar
- Tanioka, K. (1968): On the East Korean Warm Current (Tōsen Warm Current). Oceanogr. Mag.,20, 31–38.Google Scholar
- Tsuchida, T. (1979): Observations in the Japan Sea. Marine Sciences (Kaiyô Kagaku),11, 169–174 (in Japanese).Google Scholar
- Uda, M. (1934): The results of simultaneous oceanographical investigations in the Japan Sea and its adjacent waters in May and June, 1932. J. Imp. Fisher. Exp. St.,5, 57–190 (in Japanese with English abstract).Google Scholar
- Uda, M. (1936): Results of simultaneous oceanographic investigations in the Japan Sea and its adjacent waters during October and November, 1933. J. Imp. Fisher. Exp. St.,7, 91–151 (in Japanese with English abstract).Google Scholar
- Yi, S. (1970): Variations of oceanic condition and mean sea level in the Korea Strait.In, The Kuroshio. ed. byJ. C. Marr, East-West Center Press, Honolulu, pp. 125–141.Google Scholar