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Western Pacific Subarctic Boundary Currents (WSBC) comprise of Kamchatka current and Oyashio. Oyashio is divided on Coastal and Offshore Branches with a chain of big anticyclonic rings as a main feature of WSBC. Subarctic warm mesothermal water inflows to the Sea of Okhotsk through the deep Kuril Straits. Significant transformation of the subarctic water from the northern part of the Sea of Okhotsk takes place in the Kuril Basin. On the basis of observations obtained in August 1994 and WOCE data it is shown, that Kuril Basin circulation also branches at big anticyclones. It is shown that anticyclonic circulation in the Kuril Basin is divided by a chain of anticyclonic eddies with their centers along the axis of the Basin. Three anticyclonic eddies with diameter of 125-300 km in the Sea of Okhotsk are clear. Very intensive mixing is observed between different water masses inside these eddies. Stirring by eddies plays a dominant role in water mass transformation in the WSBC area.
Direction of geostrophic flow near the Strait of Boussole reflects the propagation of warm intermediate waters to the Sea of Okhotsk. Strong inflow of the Pacific warm intermediate waters to the Sea of Okhotsk observed above 500 dbar, while outflow from the Sea of Okhotsk was below 750 dbar. This warm water penetration to the Sea of Okhotsk is clearly seen in the temperature and salinity profiles. The Sea of Okhotsk waters at TS diagrams are clearly separated from the Oyashio and Kamchatka current waters by its lower temperature and higher salinity at maximum temperature. Hence the gap between TS curves for the Pacific and Sea of Okhotsk stations is clear. The feature of the Sea of Okhotsk water is high oxygen saturation. There are no minimum of oxygen in the Sea of Okhotsk near the Strait of Boussole at pressure less than 1000 dbar. Meanwhile, oxygen minimum in the Pacific to the east of the strait exists at pressure of 700-850 dbar with saturation less than 10% and absolute values less 0.7 ml/l. Therefore, oxygen concentration of 1.32-1.69 ml/l and 17-22% of saturation at 800-1000 dbar clearly confirms that there are waters originating from the Sea of Okhotsk. Comparison of several observations allows to assume the regular outflow through the Strait of Boussole at pressure greater than 800 dbar and inflow of warm subarctic waters through the Strait of Boussole and other deep straits at 300-700 dbar. High-resolution mesoscale studies are required to shed more light on the processes that control variability of the WSBC.
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