Pumping rate of a mud shrimp, Callianassa japonica, in its burrow was measured by continuous monitoring of dye concentration in the burrow water. Measurement of dilution in two directions from stained overlying seawater to normal burrow water and vice versa, gave no significant difference in results. The rate of exchange (v) of burrow water was estimated from, v=(ut-u0) V/(m-ut_-1) t, where V is volume of burrow water, u0, ut_-1 and ut is dyeconcentration of bnrrow water at time O, t-1 and t, respectively, and m is dye concentration of overlying water. The pumping rate ranged from 0.63 to 5.46ml min^-1, which corresponded to a turnover time for the burrow water of 7-51min. Short term changes in the pumping rate were correlated to intermittent behaviour of the shrimp in the burrow.

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Semigeostrophic gravity waves associated with a coastal boundary current, which has finite and uniform potential vorticity and is bounded away from the coastline by a density front on the ocean surface, are investigated. It is shown that the semigeostrophic coastal current has two waves which are named here the Semigeostrophic Coastal Wave (SCW) and the Semigeostrophic Frontal Wave (SFW). The SCW becomes an elementary Kelvin wave at some limit while the SFW is caused by the existence of the surface density front. The SCW appears mainly as variations in the upper layer depth at the coast and as alongshore velocity at the density front. On the other hand, the SFW appears mainly as variations in the width of the current. When the weak nonlinearity and ageostrophic effect are included, these semigeostrophic gravity waves satisfy the Kortweg- de Vries equation, which suggests that the local changes in the width and/or velocity of the semigeostrophic coastal current propagate as wave-like disturbances.

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The intrusion of a density current along a coast in a rotating fluid is investigated both theoretically and experimentally. The theoretical model is a shock wave solution of a semigeostrophic gravity wave which was investigated in Part 1 (Kubokawa and Hanawa, 1984). In the experimental results, the propagation speed of the leading edge of light fluid along a vertical boundary and the current width and depth are nearly equal to those estimated by the shock wave theory. The generation of a frontal wave at the leading edge of the density current is observed. The propagation velocity of these frontal waves agrees well with that of theoretically-predicted semigeostrophic gravity waves.

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A new method for the simulation of run-up using a variable transformation that fixes the shoreline is developed. This method uses equations expressed in the Eulerian description, but requires no artificial conditions at the shoreline. Hence, it may represent the real phenomenon more accurately than existing methods in which artificial conditions or extrapolation are needed. In a one-dimensional example the numerical solution is found to agree with analytic one very well. The method can easily be extended to two dimensions if the shoreline can be transformed into lines that intersect each other at right angles.

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“TIDAL VORTEX” is a term for a kind of starting vortex formed as a pair of vortices at the head of a tidal jet emanating from a narrow entrance into a bay. In this study, its formation and movement have been investigated by means of a hydraulic experiment and an analytical model. A tidal vortex is formed as a result of flow separation at the abrupt widening of a channel entrance followed by rolling up of the discontinuity surface around its free end. The vortex shows three types of life-history (type I, II and III), which are characterized by the Strouhal number and the aspect ratio of the horizontal shape of the entrance channel. In the case of type-I, the tidal vortex proceeds toward the inner region of the bay and there amalgamates with successive vortex cores into a core of tidal residual circulation. In the case of type-II, the tidal vortex core flows out into the entrance channel on the ebb but returns back into the bay on the subsequent glood. And, in the case of type-III, the tidal vortex core which was formed on the bay-side opening of the entrance channel flows out to the open sea and never comes back, whereas the core which was for med on the open-sea side of the entrance flows into the bay and never flows out. The circulation of a tidal vortex core is proportional to the reciprocal of the Strouhal number. The movement of the core near the bay entrance is determined by interaction between the cores and transportation due to the irrotational component of the tidal current. There are three types of tidal residual circulation, corresponding to three life-history types of tidal vortices. In the case of type-I, a strong tidal residual circulation is formed, but in type-II a small and weak circulation is formed. While, in type-III, the circulation having an inverse sense of rotation to that of type-I is formed.

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A method for the determination of barium in sea water was investigated using inductively coupled plasma emission spectrometry, and sea water samples from the Japan Sea and the Pacific Ocean were directly analyzed by this method. Artificial sea water was used to prepare matrix matched standard solutions to overcome the problem of physical interference. The detection limit (signal/noise ratio=2) for barium in deionized and distilled water was 0.08μgl^-1 and in sea water, 0.12μgl^-1. The reproducibilities in the purified water and in the sea water at the 10μgl^-1 level were 0.7% and 0.5%, respectively. The barium concentration in both the Japan Sea and the Pacific Ocean increased with depth and ranged between 5. 5-10.0μgl^-1 and 4.1-18.4μgl^-1, respectively.

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An ocean wind-wave prediction model MRI-II is developed on the basis of the energy balance equation which contains five energy transfer processes, namely, the input by the wind, the nonlinear transfer among the components of windsea by resonant wave-wave interactions, wave breaking, frictional dissipation and the effect of opposing winds.
The nonlinear energy transfer is expressed implicitly together with the wind effect by Toba's one-parameter representation of windsea, but neither swell-swell nor swell-windsea resonant interactions are considered.
Hypothetical assumptions are introduced to describe wave breaking effects. The numerical constant required in the assumptions of wave breaking is determined through trial test runs for a hindcast performed on the North-western Pacific Ocean.
The significant wave height, one-dimensional wave spectrum and two-dimensional wave spectrum hindcasted by this new model are in more reasonable agreement with observations than those obtained with our old model MRI.

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Since 1960 when I was a senior student, I have studied natural phenomena observed in the hydrosphere and atmosphere by means of chemical elements. Each of the phenomena is, in general, very complicated and so I have attempted to depict the whole picture of material circulation in the marine environment by studying its various aspects at the same time. My chief strategy has been to use natural radio-nuclides as clocks of various phenomena, and to use sediment traps for the determination of vertical fluxes in the ocean. The many results I have obtained can be summarized as follows.
1. I have found that several sporadic events control the material exchange through the atmosphere. These include the strong winter monsoon and typhoons that transport sea-salt particles to the Japanese Islands, the Kosa episodes that transport soil dust to the ocean, and storms that result in exchange of sparingly soluble gases such as oxygen and carbon dioxide at the air-sea interface. I have also proved quantitatively that the source of aluminosilicate material in pelagic sediments is air-borne dust.
2. I have proposed a model, Settling model, for the removal of chemical substances from the ocean and found various lines of evidence supporting the model. This model predicts the reversibility in the existing state of insoluble chemical elements in seawater among large settling particles, small suspended particles and colloidal particles that pass through a membrane filter and explains well their behavior in the ocean. I have first precisely measured calcium and iodine in the ocean and have explained their distributions on the basis of the solution and redox equilibria.
3. Using chemical tracers, I have estimated the vertical eddy diffusion coefficients to be 1.2cm² sec^-1 for the Pacific deep water, 0.5cm² sec^-1 for the deep Bering Sea water and 3-80cm² sec^-1 for the Pacific surface water, and have studied the structure of water masses in the western North Pacific and the Sea of Japan. I have also invented and applied a method for the calculation of the age of deep waters using radiocarbon.
4. I have calculated the rates of decomposition of organic matter and the regeneration rates of chemical components in the deep and bottom waters as well as coastal waters by modelling water circulation and mixing. Particulate fluxes and regeneration rates are larger in the deep waters beneath the more biologically productive surface waters. I have stressed the role of silicate in the marine ecosystem, especially in the succession of phytoplankton species.
5. I have quantitatively studied the migration of chemical elements during the early diagenesis of bottom sediments especially manganese using chemical and radiochemical techniques. Manganese is being actively recycled not only in coastal seas but also in pelagic sediments except in the highly oligotrophic subtropical ocean. This recycling can explain the formation of manganese nodules and enables us to balance the manganese budget in the ocean.

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