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11.
Numerical studies on the influence of the variations of the Kuroshio Path on the transport of fish eggs and larvae 总被引：2，自引：0，他引：2
Main spawning and nursery grounds of the Pacific Sardine are formed in the coastal boundary regions of the Kuroshio S of Kyushu
and S of Honshu, respectively. Numerical experiments on the transport and dispersion of particles in and neighbouring areas
of the Kuroshio were done to investigate the transport process of the fish eggs and larvae from the spawning ground to the
downstream nursery ground. Surface currents measured with GEK in the past were averaged for both paths with and without large
meanders of the Kuroshio in the S of Honshu and used as the data basis. Particles were released in the Kuroshio SE of Kyushu.
The results show that the transport rate of them into the S coastal waters of Honshu during large meandered path is larger
than the rate during the straight path period. However, recruitment rates of the Pacific Sardine in the S coastal waters of
Honshu decreases during the large meander periods of the Kuroshio path. This inverse correlation is considered to be caused
by the poorer food environment strongly influenced by the intrusion of the Kuroshio water. 相似文献
12.
A continuous observation system of ship drift of ferry boats was developed using Loran C, ship direction, ship speed and wind velocity measurement. A formula to estimate the wind-driven lateral drift of the boat is proposed, and a measuring system of the surface current is described, including a discussions on its usefullness to monitor day-to-day variations of the circulation patterns in the coastal boundary regions of the Kuroshio.This system was applied to observe variations of the circulation in the Kumano-nada, and Enshu-nada Seas south of Japan. Some preliminary results were obtained by using this system as well as other methods. This work focuses on the behavior of warm eddies in the Kumano-nada Sea. The surface current patterns that include these phenomena obtained by the use of the ship drift show good correspondence with currents and thermal structures observed with GEK, CTD, moored current meters and satellite thermal images. 相似文献
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15.
Naoki Nagai Kazuaki Tadokoro Kazunori Kuroda Takashige Sugimoto 《Journal of Oceanography》2006,62(5):597-606
A long-term variation in dominant species of chaetognaths in the Tsushima Warm Current was analyzed using samples collected
four times a year from 1972 to 2002 by the Maizuru Marine Observatory along the PM transect in the Japan Sea. Of 19 occurring
species, 13 subtropical species formed a major portion of the standing stock. Species richness in the study area was similar
to that in the East China Sea and the South China Sea. Four species, Sagitta minima, S. nagae, S. enflata, S. elegans dominated in the upper 150 m water column. The most dominant species per season were S. minima in both winter and autumn, S. elegans in spring and S. nagae in summer. Water temperature and salinity ranges of the most frequent occurrence for three dominant species revealed a common
tendency in the order of S. nagae > S. minima > S. enflata towards colder temperature and higher salinity. Inter-annual abundance of chaetognath species fluctuated proportionally in
response to the warm or cool phases in water temperature. Water temperature was a fundamental factor in regulating distributional
occurrence, being more decisive than salinity. Changes of both dominant species and species numbers in relation to the reduced
abundance during winter to spring and the subsequent increase during summer to autumn might be caused by specific differences
in optimum temperature. Chaetognath species are important as an indicator of water masses and significant for our understanding
of changes and evaluations of the Japan Sea ecosystem. 相似文献
16.
To investigate the fluctuation of the Kuroshio front, moored current meters were deployed near the shelf break and on the continental slope in the East China Sea, northwest of Okinawa Island, during a period from 25 June to 22 July 1984. Two mooring arrays were deployed on the slope of about 800 m water depth (under the Kuroshio), about 30 km apart along the path of the Kuroshio. Another two arrays were set near the shelf break of about 300 m water depth. The fluctuation of current on the slope is found to have a predominant period of 11–14 days and a were length of 300–350 km, propagating toward the downstream direction of the Kuroshio with a phase velocity of about 30 cm sec?1. When the Kuroshio front approaches the shelf break and the crest of the meander covers the mooring site, the current direction moves toward the downstream direction of the Kuroshio and the water temperature increases. On the other hand, when the trough of the meander covers the mooring site, the current direction changes off-shoreward across the Kuroshio or in the upstream direction of the Kuroshio, and the water temperature decreases. Three-dimensional distributions of water temperature and salinity around the mooring site were observed with a CTD twice at 5.5 days intervals, which indicate the meanders of the front is about 180° out of phase. This coincides with a period of 11–14 days obtained with the moored current meters. Wave lengths of the dominant meander of the front in the satellite thermal images were about 350 km and 100–200 km, which also coincides with results obtained with the moored current meters. 相似文献
17.
Amano A Kuwae M Agusa T Omori K Takeoka H Tanabe S Sugimoto T 《Marine environmental research》2011,71(4):247-256
This study determined the factors contributing to the spatial distribution of 14 metal concentrations in the surface sediments of Beppu Bay on the basis of comparisons of the organic geochemical properties and environmental parameters through principal component analysis (PCA) and redundancy analysis (RDA). The results of PCA and RDA showed that the concentrations of V, Cr, Co, and As were closely related to the distances between the sampling sites and the Oita River. This indicated that these metals originated from the river's drainage area. The Mn, Cu, Mo, and Cd concentrations were related to the water depth. These results indicated that the Mo, Cd, and Cu deposition processes were controlled by oxygen depletion, and that these elements accumulated in the deeper parts of the bay under anoxic conditions. 相似文献
18.
Sea surface temperature (SST) has been measured in the south of Japan using a thermometer set up in the ferry boat to investigate the characteristics of the warm water intrudes into the coastal areas from the Kuroshio. Time series analysis was applied to the SST data with satellite images and hydrographic observation data from April 1987 to September 1989. The results indicate that the warm Kuroshio water intruded into the coastal areas on the Enshu-nada and the Kumano-nada Seas intermittently with periods of about 50 and 20 days associated with the fluctuation of the Kuroshio path and the Kuroshio frontal disturbance respectively. The intrusion with a 50-day period was dominant when the Kuroshio took a stationary small meander path (B- and C-types). The warm water spread to the west at 20 cm s–1, and was estimated to have a depth of 150 m at least and supply enough heat to make up the loss due to the evaporation in the coastal area. During the straight path of the Kuroshio, it was detected that the warm water intruded into coastal areas only with a 20-day period. The warm water that intrudes with a period of 20 days spreads to the west at 25 cm s–1 in a small scale. 相似文献
19.
One year records of four current meters moored at two sites off Sanriku (39°26′ N, 142°45′ E and 143°E) have been analyzed.
Mean currents flowed southward to southwestward with velocity 2.5–7.8 cm s−1. The geostrophic velocity appeared to be surface-intensified, and the flows at 500 m depth have a relationship with the 100
m depth temperature distribution, suggesting the influence of the upper layer flows. At a depth of 1500 m and 2500 m, southward
to southwestward flows are thought to be a part of the current flowing southward on the western flank of the Japan Trench.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Takashige Sugimoto 《Journal of Oceanography》1976,32(6):297-304
I feel greatly honored to have recieved the Okada Prize of the Oceanographical Society of Japan this time. I would like to express many thanks to my teachers, and to members of our society, for their kindness provided to me up to the present.Here I have presented some of my studies which are mostly still under way. First I have presented my idea about the study on the near-shore oceanographic processes. Secondly, I have discussed about the significance and the similitude of the hydraulic model experiment, including the model experiment on the tidal mixing. Thirdly, my study on the near-shore oceanographic processes mainly by use of the hydraulic model experiment have been told. They are the effect of boundary geometries on the tidal currents and tidal mixing, the formation processes of the tidal residual circulations, the role of the air-sea boundary processes on the water-mass formation in semi-closed bays and the effect of boundary geometries on the intrusion of salt-wedge. 相似文献