The determination of dissolved Mn in sea water was carried out using a Chelex 100 resin and graphite furnace atomic absorption spectrophotometer. The nearshore surface layer waters off the Straits of Kii had the highest Mn concentration of 6.40n mol kg^-1 at these stations. Mn concentration of intermediate and deep water off the Straits of Kii ranged between 0.18 and 1.42n mol kg^-1. Mn concentration in deep and bottom waters at the Mariana Trough were between 0.71 and 2.48n mol kg^-1. Sharp increases of Mn concentration near the bottoms were observed at two stations near the hydrothermal vents of the central ridge of the Mariana Trough.

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Observations were made to study the oceanographic structure of the dense water formation and its outflow from Funka Bay, Hokkaido, during early spring. The winter Funka Bay water, which was transformed from the warm water of the Tsugaru Current, due to cooling and deep convection during the winter, flowed from the bay, while forming a frontal structure. The width and inclination of the density front were about 3n. miles and 1.4×10^-2, respectively, during the early spring of 1982. These values roughly coincided with calculated values of 2.6n. miles and 1.7×10^-2 using the sill flow model proposed by Whitehead et al.(1974). Observed current speeds and directions were also similar to those predicted by the model. The renewal time of bay water with this flow was estimated to be about 51 days, which is consistent with the results of previous studies.

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We numerically investigated the physical process of water exchange caused by fluctuations of the front. This front is formed in a vertically twodimensional NH-model (non-hydrostatic model) under steady forcing and simulates well the front observed during winter in the Kii Channel, Japan. The velocity field in the model has two kinds of oscillations. The first has a period of 6-12 hr and is caused by intermittent gravitational convection in the frontal zone. The period and the intensity of intermittent convection are determined by buoyancy flux through the side boundaries as well as surface cooling. The other is associated with large scale circulation driven at the side boundaries and is controlled by the Coriolis force and the bottom stress. Its period of 3-4 days is determined by the sum of the inertial period and the spin down time for the baroclinic mode of the along-front velocity component. These oscillations make the position of the front fluctuate with the same periods.
We next examined water exchange across the fluctuating front by numerically tracking a number of labelled particles. Intermittent convection induces exchange of particles in the frontal zone and large scale circulations transport the exchanged particles toward offshore or onshore through the lower layer. The exchange rate and the dispersion coefficient are calculated in the NH-model as 0.85 and 2.3×10³cm² sec^-1, respectively. On the other hand, in the H-model (hydrostatic model) parameterizing gravitational convections with a convective adjustment method, these values are reduced to 0.68 and 3.2×10²cm² sec^-1, respectively. This result implies that intermittent convections in the frontal zone have a large effect on water exchange across the front, and that no little water is exchanged across the fluctuating front in an actual shallow sea, such as observed in the Kii Channel.

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A Batchelor-modon eddy is a highly specialized nonlinear vortex pair, whose potential vorticity depends linearly on the stream function viewed from the coordinates moving with the translation velocity of the eddy. To generalize it, a skewed model is developed by introducing a cubic nonlinearity in addition to the linear term.
A perturbation analysis shows that the eddy region is no longer a circle but is elongated longitudinally or transversely according as the sign of the cubic term. Moreover, the eddy is slightly flattened or steepened. The cubic term increases or decreases the translation velocity, if the average radius and the amplitude are fixed.
A numerical experiment on an f-plane is carried out to show that these skewed eddies retain their initial forms even after they turn a corner of the basin; they are as stable as (first-mode) standard Batchelor-modon eddies. The present skewed model gives a reasonable qualitative interpretation of deformed eddies which result from merging of two eddies or from initially Gaussian eddies near the boundary.

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A series of measurements of winds and wind-waves were carried out in wind-wave flumes. A data analysis based on the hypothesis of local equilibrium yielded a new empirical formula on the controversial quantity of roughness height zo over the water surface: z₀: 4=1.02×10^-2 u, where the nondimensional roughness heightis defined by gzo/u² and the wave-wind parameter z₀ by wpu/g, g being the gravitational acceleration, u the friction velocity of air, the peak frequency of wind-wave spectra. The obtained formula is compared with Charnock's (1955) and Toba's (1979) proposals;o is constant in the former and inversely proportional to u in the latter. As in Toba's, this formula immediately leads to a practically important conclusion that the drag coefficient Cd depends not merely on the usual variable U₁₀ (wind velocity at 10m height over the water surface), but also on the surface state represented by wind-waves. An explicit expression is provided for the drag coefficient incorporating the wave-wind parameter; it covers the range of Cd calculated from most of the previous drag formulas, by varying the wave-wind parameter.

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