The stability properties of a baroclinic zonal current with nonlinear velocity profile are investigated. The integral method is applied to the governing eigenvalue equation having the vertical velocity as the dependent variable. Expressed in terms of the Rossby number and the Richardson number, stability criteria, unstable regions in the complex c plane, and the upper bound of the unstable wave growth rate are found. Some differences in the results are noted between the present model and the quasi-geostrophic streamfunction model, particularly in connection with the effect of the velocity profile curvature term U_zz. It is conjectured in the present model that, depending on extreme behaviors of U_zz, the propagation speed of unstable waves can be greater than U_max or smaller than U_min.

View full abstract

Using the data from a wind-tunnel experiment, bispectra of orbital-motions of wind-waves and of turbulence are calculated, and nonlinear interaction of wind-waves with turbulence in water are discussed. The wind-waves or the orbital motions of them, at first, produce the “turbulence” coherent with themselves, and then this “coherent turbulence” changes to the “turbulence” noncoherent with wind-waves. Nonlinearity of the velocity fluctuations in the surface layer in water under wind-waves is almost due to the nonlinear energy transfer from the orbital motions of wind-waves to the “coherent turbulence”. The vertical variations of the power spectra and of the normalized bispectra suggest that the wind driven currents near the surface play an important role in the process from orbital motion of wind-waves to noncoherent turbulence.

View full abstract

Southwestward volume transport (referred to 1, 500 db) out of the Gulf of Alaska seaward of the continental shelf in May 1972 was 12.5 Sv, and nearly 3/4 of this flow occurred within 50km of the shelf edge. Mean geostrophic velocities of about 50cm s^-1 occurred in a band 20km wide, which extended 500km along the shelf edge; a maximum velocity of 98cm s^-1 (nearly 2 knots) was obtained. Bottom flow along the inshore part of the shelf as determined by seabed drifters was generally onshore at 0.5cm s^-1. Evidence is presented of a large cyclonic gyre on the shelf encompassing the Portlock and Albatross Banks, perturbations in surface flow along the shelf edge, and relations between coastal tidal heights and fluctuations in geopotential topography at the shelf edge.

View full abstract

Regional and vertical distribution of the microzooplankton in the Philippine and the Celebes Seas is reported in relation to the phytoplankton distribution. The maximum concentration of chlorophyll a occurred at the surface in the Celebes Sea and in subsurface layer (50-150m depth) in the Philippine Sea. On the other hand, the maximum occurrence of the microzooplankton was observed in the subsurface layer (50-150m) throughout these sea areas; discrepancy in the vertical positions of the chlorophyll α and microzooplankton maxima was observed in the former sea area. The higher dominancy of large-sized phytoplankton such as diatoms and Trichodesmium at the surface maximum, probably because most large-sized phytoplankton were uningestible for the microzooplankton, was the main reason why the discrepancy existed in the Celebes Sea. In the Philippine Sea, where the subsurface chlorophyll a maximum layer was formed mainly by small-sized phytoplankton such as coccolithophorids and small dinoflagellates, such a discrepancy was not observed. These may indicate the establishment of a close food relationship between the microzooplankton and the small-sized phytoplankton rather than to the large-sized phytoplankton.

View full abstract

The heat lability of succinic dehydrogenase, malic dehydrogenase and lactate dehydrogenase in cell-free extracts of Vibrio marinus MP-1 grown at 15°C was compared for the tris buffer suspended enzymes and the NaCl suspended enzymes. The tris buffer suspended enzymes lost 50 percent activity at low thermal exposure between 5°C and 27°C. No activity was evident on thermal exposure between 32°C and 39°C. The enzyme extracts suspended in NaCl at 36 700 were more heat stable, losing 50 percent activity after exposure between 16°C and 40°C. The enzymes lost all activity on thermal exposure between 33°C and 42°C in the presence of NaCl.

View full abstract

The annual net and gross primary production by phytoplankton in Akkeshi Bay Hokkaido, are estimated to be 146±25g C m^-2 and 416±53g C m^-2 y^-1 respectively. The annual means of the net and gross efficiency between primary production and solar radiation are estimated to be 0.26% and 0.79%, respectively.

View full abstract

Semi-diurnal tides in the Yellow Sea are calculated by integrating the shallow water wave equations with frictional and inertial terms.
It is found that the results depend on the bottom friction. In the frictionless case the tidal range is unstably amplified because of the occurrence of resonance of the semi-diurnal tidal component in Inchon Bay. When the bottom friction is in the form of the square of velocity, the results agree fairly well with the observations.
The following results are obtained. First, the tidal range is larger at the coast of the Korean Peninsula than at the China Coast. Second, resonance of the semi-diurnal tide occurs in Inchon Bay. Third, bottom friction is very important in the shallow ocean, i.e., when the bottom friction become large, the phase lag is retarded and the tidal range decreases.
The amplitude and the phase lag calculated in this study agree well with the observations in the case of τ_b=γ_b²V|V|, γ_b²=0.0026, especially in the coast of the Korean Peninsula.

View full abstract

[in Japanese]

View full abstract