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131.
Takashi Ichiye 《Pure and Applied Geophysics》1966,63(1):179-195
Summary A layer of a few hundred meters thickness with suspended matter (a nepheloid zone) was discovered byEwing andThorndike [4]3) near the bottom on the continental slope of the North Atlantic. A downward pressure gradient is produced in this layer due to increment of water density with suspensoid. When only the Coriolis force balances with this pressure gradient, a bottom nepheloid current flows southwestward parallel to the depth contours with a velocity of about 10 (cm/sec) for a slope of one degree. The pressure gradient for fluid with locally variable density above a sloping bottom is treated and an extra term due to density gradient along the slope is derived. The vertical profiles of the nepheloid current with an effect on the vertical eddy viscosity are computed. Two kinds of vertical distributions of eddy viscosity are determined from the observed nepheloid distributions and used in the calculations: constant but different values at two layers and those increasing with height. The effect of the change of density along the bottom is treated by introducing dimensionless variables. Rossby number of the nepheloid current becomes about 10–2 indicating inertia terms to be negligible. Rossby number of turbidity currents ranges from 2 (in a decaying area) to 5 (developing area), suggesting that inertia terms are more important than Coriolis terms. The trajectories of turbidity currents are computed from motion of a mass of mud under the Coriolis force and friction, and the results are applied to those inferred byHand andEmery [6] in the San Diego Through off California.LGO Contribution Number 925. 相似文献
132.
Distribution of nano-phytoplankton was studied during May–June 1971 in the subtropical northwestern Philippine Sea. Plankton samples were collected at various depths between 0 and 200 m. A gentle gravity filtration technique was employed to concentrate the samples. They were then examined without fixation under a microscope. The average cell number of total nano-phytoplankton was 1×1042×104/l, and nano-flagellate cell number often accounted for more than 90% of the total cell number of nano-phytoplankton, consisting mainly ofGymnodinium lacustre, Amphidinium sp., and unidentified small nano-flagellates. The distribution of nano-phytoplankton did not correlate with vertical profiles of chlorophylla. 相似文献
133.
Yoshinobu Wakata Takashi Setou Ikuo Kaneko Hiroshi Uchida Shiro Imawaki 《Journal of Oceanography》2006,62(1):25-35
The interannual variability of the Kuroshio volume transport passing through the 137°E meridian south of Japan was simulated
with an ocean general circulation model (OGCM). The time series of the Kuroshio volume transport over the 1000 m depth in
the OGCM is well reproduced by the one-dimensional quasi-geostrophic (QG) vorticity equation with a windstress forcing. In
our analysis of the OGCM and QG results, we found that peaks and troughs of the time series of the Kuroshio volume transport
with 2–3 yr time-scale were induced by windstress curl, both local and immediately eastward, whereas longer time-scale variability
was also induced by windstress curl near the dateline. 相似文献
134.
Masanori Konda Norihisa Imasato Katsuya Nishi Takashi Toda 《Journal of Oceanography》1994,50(1):17-30
The sea surface emissivity in the infrared region is determined on the basis of data analyses. Net radiation, surface irradiance and other oceanographical and meteorological variables are measured throughout most of the year at the oceanographical observatory tower in Tanabe Bay, Japan. We have found that 0.984±0.004 is a reliable emissivity value from the night time data. Surface emission radiates not from the subsurface water but from the sea surface. The thermal skin layer on the sea surface, however, is disturbed and disappears under high wind speed over 5 m/s through the analyses of the radiation observation using the emissivity value of 0.984. Under low wind speed, the sea surface can be cooler or warmer than the subsurface due to overlying thermal conditions and the skin layer can be neutral as the transient process between them. By using an emissivity value of 0.984, the temperature difference between the sea surface temperature and the temperature determined from surface irradiance that has been reported in the satellite data analyses is found to be reduced by half. 相似文献
135.
Concentrations of 12 trace elements (V, Cr, Mn, Cu, Zn, Se, Rb, Sr, Cd, Cs, Ba, and Hg) were determined in liver and skin tissues of minke whales from various regions within the Antarctic Ocean. Cd concentrations in livers of southern minke whale were apparently higher than those in cetaceans from other regions, while Hg concentrations were lower. There were significant positive correlations between body length and concentrations of Cd and Hg in the liver. The concentrations of all trace elements in the skin were lower than those in other cetaceans reported previously. Significant positive correlations between liver and skin were found for Cr, Mn, Cu, Zn, Rb, Cd, and Cs, implying that the concentrations of these trace elements in the skin reflect those of internal organs. Large interannual variation of the accumulation pattern of trace elements in the skin was observed for the southern minke whales from Area V. There were significant differences in the skin element concentrations among Areas III, IV, and V, especially for males. Also, discriminant analysis between geographically two different groups collected during 1995/1996 austral summer season, based on the concentrations of trace elements in the skin, allowed for a correct classification of 90% of these minke whales. These results suggest that measurement of trace elements in skin samples could provide valuable information on the status of contamination and possible geographic differences in the accumulation levels in southern minke whales. 相似文献
136.
Larry P. Atkinson Jackson O. Blanton Charles McClain Thomas N. Lee Masayuki Takahashi Takashi Ishimaru Joji Ishizaka 《Journal of Oceanography》1987,43(2):89-103
Hydrographic observations between the Izu Peninsula and Oshima Island, Japan, in May 1982, showed upwelling around the tip of the Peninsula and possibly also in the lee of Oshima Island. The upwelling introduced water as cold as 18 C with nitrate concentrations of 3M to the surface. Temperature/salinity analyses indicated that the upwelled water was of Kuroshio characteristics. Slightly fresher water was advected out of Sagami Bay in a coastal counter current.Contribution number 470 from the Shimoda Marine Research Center, University of Tsukuba. 相似文献
137.
138.
Material transport through the shelf edge to the deep ocean determines the fate of particulate matter generated in productive coastal seas. In stratified estuaries, onshore flow in the bottom layer generally keeps particulate matter generated in the upper layer and settled down to the bottom layer within the estuaries. AT the shelf edge of Tokyo Bay under the condition of average onshore flow in the bottom layer, we observed higher vertical sediment flux during ebb than flood tidal currents. The on-shelf and off-shelf differences in turbulent mixing and water depth mainly cause such difference in sediment flux. We propose to call this export process of particulate matter the tidal pump at the shelf edge. 相似文献
139.
140.
The regional distribution of dinoflagellates was investigated in the surface waters surrounding Hokkaido in May, August, and October, 1983. Among the total of 92 species identified, 37 species appeared throughout the investigation period. A similarity analysis identified six assemblages at Cλ=0.66. It was shown that each assemblage was closely related to the currents and the water temperature. Assemblage I consisted of 80% of the total samples and was subdivided into two groups-cold and warm water species in the Tsushima Current. Cold water species were widely spread in the Tsushima and Soya Currents in May and shifted to the Low Saline Water in October while warm water species were dominant in the Tsushima and Soya Currents in October. The regional abundance of shellfish toxic dinoflagellates,Dinophysis fortii andProtogonyaulax tamarensis, was also revealed. 相似文献