Interaction between the turbulence and the wave-induced air disturbances is treated by use of the mass and momentum conservation equations and the rapid distortion assumption. Assuming the correlation functions of the velocity derivatives, growth rates of waves are calculated. The growth rate obtained for the reasonable values of parameters shows the agreement with that obtained in the laboratory experiment by KENDALL (1970) and in the field experiments.

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Direct observations of thermal microstructure within the main stream of the Kuroshio show that within the region of the most steeply sloping isotherms, from about 180 to 360 m depth near the current axis, considerable microstructure is present, and the laminae tend to be approximately aligned along the sloping isothermal surfaces rather than horizontally. Away from the axis, the slopes of the isotherms are considerably less so that the tendency for alignment along isotherms, if present, is not noticeable. Laminae rarely if ever extend for as much as 6 miles in the cross-current direction. Lateral temperature variations within individual laminae are small; to the extent that they do occur there is no apparent tendency for density to be conserved.
Some of the temperature features seem to correspond to small local maxima in the vertical salinity profile. More experimental evidence and better understanding of STD spiking (from causes other than the time-constant mismatch, which is clearly not the cause here) is required before it can be concluded that these local maxima are real. If real, they would provide evidence that local vertical mixing alone cannot produce the thermal microstructure in this region. The main conclusion, however, is that STD salinity measurements are not very reliable at the present time.

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Dynamical properties of short-period temperature fluctuations are studied. Water temperature was measured continuously at several depths at the following stations: at 38°29.5'N, 141°35.8'E (100 m depth) on the continental shelf off Miyagi Prefecture in the summer of 1967, at 35°01.8'N, 139°0.8.5'E (100 m depth) in Sagami Bay in the summer of 1968, and at 32°32.2'N, 129°53.7'E (74 m depth) in Tachibana Bay in the summer of 1970. These measurements were made with a thermistor array laid down from the R. V. Tanseiinaru (Ocean Research Institute, University of Tokyo) which was fixed with bow and stern anchors. Significant temperature fluctuations found at the first and the third stations are thought to be due to first mode internal waves having amplitude 3 to 5 m and period 5 to 20minutes. The wave length of the waves is estimated to be 25m to 400m from the observed density structure. At the second station, we found second-mode internal waves. The period, amplitude and -wave length of the waves are about 30minutes, 1.3m and 600m, respectively. In all cases, the spectral density of the temperature fluctuations decreases with increase in frequency. However, the decrease obey neither the -3 power law nor the -5/3 power law. Coherences in the temperature fluctuations between two depths of measurement in the seasonal thermocline are significantly high in the range of frequencies lower than the local Brunt-Vaisalii frequency, but are low in the higher frequency range. At the first and the third stations, the difference in the level of coherences between the lower frequencies and the higher frequencies are large. Phase differences between two depths in the thermocline are small in the lower frequency range. This suggests that the first-mode internal waves are predominant over higher-mode internal waves and over other disturbances.

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Chl α, protein, RNA and DNA were measured in 400 samples taken from the surface down to 5, 000m at 27 oceanographical stations in the North Pacific Ocean. Two section diagrams of these cellular constituents were given along 155°E and 155°W meridians, and several vertical profiles of the four constituents were also given at some stations near Japan. The average concentration ranges of Chl α, protein, RNA and DNA obtained in this study area were 0.025-0.862, 11.4-88.1, 1.36-35.3 and 0.13-5.24μg/l, respectively. Chl α was distributed mostly in the photic zone as we would expect. However protein, RNA were in high concentrations within the photic zone and sometimes extremely high concentrations in the deep aphotic zone.

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About 10⁶ of total bacteria (direct microscopic count) or heterotrophic bacteria (colony count with Medium 2216E) and about 104 of petroleumlytic bacteria (oil-oxidizing bacteria) were enumerated per square centimeter of the surface of petroleum globules suspended in the topmost 10 meters of water from a station (22°00.2'N, 125°51.9'E) in the western North Pacific central water, where about 10⁷ of total bacteria, about 103 of heterotrophic bacteria and about 10 of petroleumlytic bacteria were enumerated per liter of seawater.

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