Some numerical experiments are made using a linear barotropic model of Lake Biwato investigate the current induced by the spatially uniform wind stress. Concerning the phenomena whose time scale is longer than the inertial period, we integrate the nondivergent vorticity equation.
It is found that the “topographic curl” of the wind stress which comes from the bottom topography and the wind stress induces circular currents and that the current, generated by the wind, attenuates gradually accompanying the topographic Rossby wave whose periodis about 9 half-pendulum days in Lake Biwa. This mechanism of the barotropic response of the lake water to the wind will explain well the unsteady lake current in Lake Biwa in winter.

View full abstract

Characteristics of seiches in Onagawa Bay are investigated on the basis of observations at the bay head, Konorihama, from May 1972 to May 1973 and at the outside of the bay, Enoshima during the same period.
At Konorihama seiches with the double amplitude of 7 to 11 cm occurred most frequently (63 percent of the total samples) and the maximum reached 31 cm.
Short-time spectral analyses indicate that the periods of the spectral peaks shift considerably with the lapse of time, and that the location of the nodal line near the bay mouth moves offshore and inshore of Enoshima. The cause of these phenomena seems to be attributed to the change of incident angle of waves coming from the open sea to excite seiches.Amplitudes of the fundamental and of the lateral modes of seiches increase or decrease alternately with time, suggesting the energy transfer between these modes.
Bay oscillations induced by remarkable atmospheric pressure-waves were observed. However, the amplitudes of the oscillations were within a few centimeters and dissipated in a few hours.

View full abstract

The yearly variations of mean sea levels at various locations along the coasts of Japan have been investigated, based upon the data of observation taken at 55 tide-gauge stations from 1953 to 1970, and some discussions have been made on therelationships between those variations and meteorological and oceanographical conditions, etc. The results obtained are as follows:
1) In cases covering 90 %of all the tide-gauge stations, the magnitude of the annual mean rate of variation of ground level is less than 10 mm/year, and the mean value of the magnitude for all the stations is -3.17 mm/year, while that exclusive of Osaka is -1.7 mm/year.
2) The effect of atmospheric pressure variation on the height of annualmean sea level is of the order of several centimeters in view from both time andplace.
3) In view of the characteristic types of variations, the coasts of Japan may be divided into five regions of similar mean sea level deviations. And in the yearly variations of mean sea levels, there can be seen a kind of variation which corresponds to the variation of oceanographical conditions such as abnormal fall of seawater temperature.
4) The mean sea level deviations at variouslocations along the coasts of Japan, referred tothe standard sea level “T.P.” are different for different places. Namely, (1) onthe coast of the Japan Sea, the west coast of Kyushu, the coast of Sanriku and the coast of Hokkaido, the mean sea level is higher than on the Pacific coasts from Southern Kyushu to Southern Honshu.(2) Along the coast of the Seto-Inland Sea, the mean sea level is generally higher.
As for the leading causes of the above deviations, we may safely enumerate the following ones, viz.(a) the effect of the deflecting force of the earth's rotation on currents, and (b) the effect ofvariation of seawater density. However, as regards the relative importance of these two effects, no decisive conclusion can yet be given for the present.

View full abstract

Responding to the recommendation at the first Meeting of the International Coordination Group for the Cooperative Study of the Kuroshio and Adjacent Regions (CSK) 1965, a series of nitrate standard solutions consisting of eight different concentrations ranging from 0 to 50 μg-at NO₃-N/1 in 30.5‰ sodium chloride solution with the highest purity was prepared for nitrate-N determination in seawater. The solutions have been proved to be stable at least 520 days after preparation.
The best way of handling and conditioning the copper-cadmium column was studied for securing the perfect and reproducible conversion of nitrate to nitrite for the procedure as proposed by WOOD et al. (1967).
It was also shown that the method can be applied to freshwater samples by the addition of sodium chloride and adjusting p H properly.

View full abstract

Water surface elevations η(t), vertical surface velocities η(t) and vertical surface acceleration η(t) of wind-generated waves have been measured in a laboratory wind wave channel by using resistance-type wave gauges combined with an electronic differentiation circuits. Probability distributions of the values of η(t), η(t), and η(t) have been determined from the wave records.
In an initial stage of wave generation, i. e., when wind waves are generated at short fetches and low wind speeds, the observed distributions for η(t), η(t) and. η(t) are appreciately good fit to the distributions given by successive sum of a Gram-Charlier series, which has been derived following the formulation of LONGUET-HIGGINS (1963), by taking the weakly nonlinear effect into account.
However, when wind waves develop with increasing wind speeds and fetches, the observed distributions deviate gradually from the Gram-Charlier series. Particularly, the deviations are remarkable for the distribution of η(t).
When the wind speed increases, the observed distributions of η(t), η(t) and η(t) show. the following characteristics:(i) the skewnesses of the distributions of η(t) and η(t) decrease slightly, (ii) the skewness of η(t) changes, at some wind speed, from positive small values to relatively large negative values.(iii) the kurtosis of the distribution of η(t) decreases slightly but that of η(t) increases slightly and these characteristics seem to depend not so much on fetches, (iv) the kurtosis of the distribution of η(t) increases rapidly.

View full abstract

The finite difference analog of the linear vorticity equation for the mass transport in the ocean does not hold good unless the grid size is smaller than a certain number.

View full abstract